another compression ratio question

[stknrdr]

Making a long story short here, my 350 has about 10k miles on it from a (i thought) professional rebuild. Started running poorly so I compression tested and voila two dead cylinders. Pulled the heads off and sure enough 2 burnt valves (middle two cylinders, right hand side). Of course the engine is out of warrantly, so i guess its a good excuse for vortec heads.

When I pulled off the heads, I noticed that my supposed to be flattop pistons were, in fact dished. I called the rebuilder to tryand find out how many cc's of dish they have so I can calculate a compression ratio for the vortec heads....they didnt know, but said they are same as stock and the compression ratio for dished pistons and a 76cc head should be 8.5:1 - so by playing with the compression ratio calculator I come up with about 12 cc's of dish.

Does this sound correct?

If so, the builders mistake may be a blessing in disguise as with the dish ill be under 10:1 with the vortecs. I'm just trying to figure it out as exactly as I can with what info I can muster up.

Im trying to figure out what kind of hp and torque improvement to expect, this engine has always been a bit lackluster and now I know why.

Anyway here are the specs, any guesses on what the Hp/torque numbers should be?

350 - .030 over
edelbrock performer intake, performer carb (1406)
headers, 2.5'' exhaust with flowmaster 40's
cam 206/214 duration .432/.453 lift
vortec heads (yes i upgraded the springs)
apparently stock dish on the pistons