Have vortec heads and currently have flat top piston with 4 reliefs which came with the shortblock. Should I have the heads milled or get domed/dished pistons?

 

Why do you want to do this? Do you really need to increase the CR? What is it now?

Do not get dome pistons they are the worst possible thing you could do. Dome pistons are a crappy crutch for mismatched parts.

 

Is the problem that you have a 305 engine and now you're way down on compression?

Milling the head and running a .015" head gasket would raise compression considerably.

New pistons would be nice for durability reasons but the cost would be: New pistons+ basic engine overhaul+ Assembly.

Do some calculating with a milled head and thin gasket first of course, or have someone do it that knows more than you. I would try to stay at or near 9.5:1 Comp. ratio also. Goodluck!

 

1st, thanks for the responses. I used a free program from www.performancetrends,com to compute my compressions and came with a compression of 10.81. This is to much compression for an iron head that is to be used as daily/street engine. I am new to all this so I may have entered the wrong information. Here is some info on the engine:
350 bored .040
Flat top piston w/4 reliefs 6cc
Vortec heads 64 cc
Gaskets I entered .0.15
Deck height is 0
Will be using a lt4 hot cam

 

So you don't want to lraise your compression, you want to lower it. Get it different head gasket that is around .04" so that you will have optimum quench with 0 decked block.

 

I meant to lower not raise, thanks for bringing that out. Even with a .040 the comression comes to 10.16. Isn't that still high for pump gas?