I just bought a 1970 Lemans shell (car had no engine, transmission, or interior) and was looking to install a drivetrain.  I have 2 possible options easily at my disposal.

1) I have a 1968 Pontiac 350 that I bought as a usable core.

2) I have a nearly new (less than 2000 miles) Chevy 454.

My questions are 1) Which engine should I choose and 2) Where would I be able to get the engine mounts for these engines?

Thanks in advance

The mounts I am speaking of are the frame mounts not the motor mounts.  

To my knowledge an '68 ss396 chevelle should have the mounts you need if you go chevy.  Personally, I think pontiac olds and buick are cool so I'd find a 455 and wedge it in there.

it depends on what your doing with the vehicle and if you want to keep it all pontiac,granted thta's what you want to do carcraft did a issue on a pontiac 350 build up that produced some dam stout numbers for a small block. but if hat doesn't matter to you and you just want power the big block is a good start yes it's heavier but so is that car and with the right parts big torque and horsepower will be eay to achieve so good luck  

Wow - that's a real stumper.  I personally like the idea of using all Pontiac stuff to keep it more original.  Besides that, there are some real good engine choices out there that have me pretty facinated with the Pontiac mills.  The 455 is a no brainer and there is copius amounts of material in print and on the web on how to build that big boy.

 I also know that money counts.  If you own the 454 outright, and know the 2000 miles is legit with no "well it knocked a little" type statements tied to it, then that's kind of hard not to use.  The 454 is going to be much heavier than the 350, so you are going to have to change springs in the front end.  You would have to if using a 455 Pontiac as far as that goes, but it's all doable. 

As far as engine mounts and the like, I'd go to a junkyard and pull some out of a Chevelle.  Depending on the transmission you are going with, the cross member will be different like between a TH-350 and a TH-400.  If you are wanting to go with a four speed automatic, the 200-4R will be a direct change with the TH-350 - including the driveline yolk.  The TH-400 will have a different yolk that is compatible with the 700-R4.  Either way you go on it you can't loose.  The reworked 200-4R is actually a stronger unit than the 700-R4 and that's so says my transmission man who is a GM factory trained transmission guy. 

One word of advice would be to say that you might want to evaluate what the 454 was used for prior to mothballing.  Also, how was it mothballed?  Clean oil in the crank case and oil in the cylinders can go a long way in preventing any unseen damage from occurring.  The other thing is if the 454 is set up the way you want?  It's out of the car, now is the time to re-cam and do those things that tend to be a pain in the a@@ after the engine is put in the car.

Let us know what you decide.  Sounds like you have a good project going.

Bowser

The 454 was used in a van prior to removal.  The gentleman I purchased it from had the engine stripped apart and took it to a machine shop to be checked out, magnafluxed, had larger valves installed, new cam, and had roller rockers installed.  The engine came almost right from the machine shop to my garage, where I assembled it and gave it a coating of oil and have it on an engine stand since.

As far as the transmission choices go I have both a TH350 and 400 in storage with the needed crossmembers for each..

I have bought the motor mounts for a big block Chevelle and are awaiting their arrival (my area doesn't have that many classic car junkyards).

I am actually thinking of possibly putting the 454 in for the time being and later putting a Pontiac engine in.

I'm all for a Pontiac motor in a Pontiac but if you have a 454 laying there all ready to go then use it.  I doubt you were wanting a full resto anyway  

I think that is a good plan you got going.  As far as the transmission goes, both the TH-350 and 400 are good.  You should just go with the freshest one that will need the least work.  TH-350s can be made very stout - I am using one on my '67 Cutlass and my small block is probably pushing 425 hp at the wheels.  I have never dynoed the thing (yet).  We estimated 450 at the flywheel and you are going to lose some through the drive train, so it may be a little less than 425.  My transmission man told me he built it stout enough for about 500 hp, and 400 ft lbs of torque using pump gas, so kind of guage your decision on that.  The big block is going to put out mass torque, so if your TH-400 is fresh then use it.  You can buy 400 yolks through Summit for cheap. The advantage of the TH-350 is that it is about 75 pounds lighter than the TH-400.  It also uses less HP to turn (with the TH-400 you lose about 40 hp), but the 400 is the bullet proof standard.  Depending on your cam, I would choose a torque converter with a stall of no higher than 2500 RPMs for the sake of streetability.  You get around 3000 RPMs, then slippage becomes a problem and that means heat build up.  That will kill a tranny pretty fast.  On the strip, that's what you want is a high stall, but in town, keep the thing decent to drive.

As for a Pontiac conversion - sure.  Make it a long term project since it sounds like you are getting a mighty good mill put together as it is.  When the 454 pukes, you are ready to mount in your Pontiac mill.  One word of caution on that is the bell housings don't interchange.  Have a tranny ready to go with your Pontiac engine when the other one dies.

Have fun.  Sounds like a great project.  Bowser

stay poncho ,but find a good 455 ,455>454

I would( like several other people have said) keep it all pontiac, but I would have to go with the chevy unless you could sell it. Check into a  muti fit bell housing trans. I use a muti fit tubo 350 in my chevy nova. They can be found in all types of gm cars. This would make it easy to change engines if you wanted  to at a later date.

First of all someone said the 350 Pontiac is a small block. It is NOT. Pontiac never made a small block or a big block. They made Pontiac engines. They all weigh about the same too. From 326-455. Same deck height, 10.2 inches. Now they did make a SHORT DECK engine which was the 265-301 from 79-81.
    Check with Rock and Roll Engineering. They made 540 hp with a 350 Pontiac and then with nitrous it made 670.  

im die hard poncho, but i say 454 definently !! get chevelle motor mounts for big blok chev for same year 'velle!  if anybody pokes fun at you choke them out with blue tire smoke!!!  

It's a tough call but I've got to go with the 454. Like some of the others I'm a Pontiac guy myself but common sense says the easiest and likely less expensive way to go is with the Chevy. Just a word of caution...depending on what was it the car to start with the cooling system may need some upgrade. Make sure the rad is big enough to cool that big block. Have fun !!