Its my first time in this forum,and Im shocked.CarCraft
is a great magazine and its website deserve more respect.Im a mechanic and read CarCraft for at least 15 years and certainly I learned a lot during this years with CarCraft,so I recommend some guys here to read more before type their knowledge.  

TO importsstillsuck,thanks.  I have flat top pistons and shaved heads .010 off bottom,187 valves,58cc heads. I have either detonation or compression rattle,so 194/160 valve heads will help. Plus i need to reduce compression a small amount. With gas at 3.59 per gallon. I can use 87 octane fuel.  

alright man, do what you gotta do, but when i put 350 heads on my old 305, that thing wouldn't get out of its own way, so be careful man, calculate ur compression before you do it, like i should have done...  

This is an interesting subject, but I think it has to do with manufacturing reasons. Supply demand, money overhead blah blah blah. They are running a business, so it best suits them to make a piston a certain way that might appeal to the popular crowd. And it goes the same way for you, you have to pick the piston that best suits your need. Figure out if you even need a valve relief in the first place, if you do, figure out just how many you need. Most manufactures will custom make a piston with 10 valve reliefs, just as long you can explain to them why you might need such a thing.  

Also, 350 heads on a 305 sounds wrong. Anyone with me?  

350 heads on a 305. Who needs compression?  

To GIBTG. I am curious,Does your post mean 350 heads on 305 are a plus or a minus? I know there is a considerable compression difference in heads(as importstillsuck stated). But is it worth it to change power wise? I am always open to advice.If i was more familiar in 2001,I would have used 350 instead of 305.  

The large majority of Gen I 350 heads had 76cc chambers, compare this to the 55-60cc chambers that were used on 305's, and the fact that the 305 gives up 45 cubic inches and you can see the static compression would be very low, so at this point it's a disadvantage. An advantage would be that most 350 heads had a slightly larger port and valve than 305 heads, but this difference is not significant enough to use domes on a 305 to get more than 8.0:1 compression.

The best thing to do for a 305 is to get an aftermarket head with improved ports and a small chamber. Some have heavily milled vortec heads, but there are other heads on the market that will make the same if not better power than Vortecs without extra machine work. But we have to remember that we are dealing with a 305 and that we shouldn't be working very hard on them.  

Thanks gib and importsstillsuck.  

My 305 has flat tops,but i am forced to sell 79 Monte-Carlo and buy a 28 or 30 mpg car because of 3.90 per gallon gas,AS i hope this don't also affect too many other muscle car owners.  

Well, I am back. Going to the beach(5th year anniversary)    to relax an play for a week. I Turned down $1,500.00 For 79 M/Carlo. I decided to put in 440 lift crane cam,new lifters,and true 2.25" dual exhaust out back. plus I am changing rear end from 2.29 differential to 3.08. I got lucky.I found wrecked car with dual Exhaust on car in good condition with rear end in good shape for 200.00,Plus price for cam kit and intake gasket.My oil pan gasket is one piece blue rubber,And i already had spare valve cover.front seal,timing cover,and exhaust gaskets.My water pump needed replacing.So I would have had to remove these parts regardless. So I felt this was my smartest and cheapest route for better performance,plus I drive this car around town more than over the open road ,since i now have small car to drive to work(corolla,32 mpg).