Yea, if the OP is sure that the engine is currently 11:1 with stock 72cc 317's on it, then his SCR will increase dramatically when he installs most of the smaller combution chamber aftermarket heads out there, unless he gets the 317's worked or gets some WCCH StageII 317's, which have about a 74cc combustion chamber if they are not milled....

But basically, since he's not sure what heads he will be running, he really can't state what compression ratio the engine has...

 

ding ding ding, someone read the post before he replied. the guy i bought it off of needed money and offed the build midway through. i have a complete turnkey motor if i was to put the stock **** back on it. but im not.
so my ??? to u guys was: what after market head and custom cam will get me closer to my goal of 450-500 rwhp? keep in mind the pistons are diamond 11 to 1 comp so i would like to match the heads to them to keep the compression.

 

I read the original post.

The pistons are only 11 to 1 when used with a specific size combustion chamber. We need to know more about which pistons you actually have in order to recommend heads. Are they domed, flat-top, dished, etc. And by how many cc?

 

diamond pistons specs part #11519
chevy ls1 street/strip flat top
bore= 4.030
stroke= 4.000
effective volume= -1.8cc
comp height= 1.125
rod length= 6.125

 

here is an engine size/ compression calculator
http://www.race-cars.net/calculators...alculator.html

 

From the calculator i used with l92 heads you would have 11.77. Put on a set of l92 heads i know of an fbody somewhat local with a 408 with stock l92 heads and l76 intake with the same cam i have running 10.80s

 

That sounds like a good combo.