I have the option to buy a Mark V BBC that has been bored 60 over for $250.  This just kinda fell in my lap today and I havent had the chance to properly research all the series of the big blocks to see what the pros and cons are of each.  I'm calling on everyone's knowledge in these forums to give me a yay or neigh on this.  If I do end up getting this block it will be used to build a twin turbocharged engine for my 55 chevy.  I have some concerns with the 60 overbore and the added cylinder pressures that comes with supercharging.  I guess the real question is, is this block going to be a good canidate for me?  I'm not sure of the deck height, I'll see if I can call the guy and get that later in the week.  Thanks in advance for any/all advice/insight.  

that motor would work fine for a n/a combo but you want to twin turbo the motor i would go with an aftermarket block from dart or motown i know the're expensive but your getting added strenght and other options that dont come on standard gm blocks i hope this answers your question.  

Yeah, I know that the Motown blocks are stronger but does the cheapness of this block off-set those bonuses?  

What we need to know here is the kind of BBC this thing is.That much oxidation will require a 4 bolt main with a forged crankshaft.060 over should not B an issue.I've seen 454's bored .080 on 250 shot of NOS.  

it would be a good idea to have it sonic checked.this will tell you the wall thickness.you could also partial fill the cylinders w/ block filler.(be sure to rehone after to be safe!)  

The sonic test is good advice if hes sure its the right block.