Ok i know this has been talked about alot , but i kind of a more specific question. Im building a 383 Vortec for my street car . I have flat top pistons ( 4 valve reliefs ) Would my compression be too high for pump gas ??

Even if Vortecs really were 64cc as they're claimed to be, you would still be around 11:1 compression. However, by the time you get them lightly cleaned up (a .006" shave off the decks) you're at about 60-61cc. unless you're in Denver, AND running a bottom-of-the-page camshaft, that's too much compression. Either get some pistons with at least an 18cc dish, or pick some aluminum heads with at least 72cc combustion chambers.

Thanks alot for the reply . What pistons would you recommend ?

What would be wisest depends on a few other factors. If you're lloking at a zero-decked block, that would rule out the Keith Black hypereutectic pistons, because then they would be about .007-.010" out of the holes at top dead center. While that could be countered with .051"-thick head gaskets, that's to be avoided when possible. Also, will you ever be adding nitrous, or boost, or both If so, you'll definitely need to get Forged pistons. And there are 2 kinds of materials used in forgings. 2618 is what you would want, you can tell 2618 apart from 4032 by the piston-to-wall clearance specified. 4032 can run about .015", while 2618 runs about .005".