When you suggest to use GM fast burn heads on a 383 to make 600 hp, that is not doing homework. When you then mention you can get them for 675 in summit that is a clear indication that you do not have the means to support your desires. Not taking shots at you, just making an observation.
Here is something I found real quick, I don't know these guys or anything just for some quick numbers:
http://www.cmengines.com/Engines/Str...5/Default.aspx
Notice the 383 is not offered above 500 hp.
Notice the 434 is used beyond that point, because the cubes make it easier to make the power. This was suggested by others. The 434 comes with a "new" block, meaning aftermarket, this was suggested by others. And you are still short of 600hp and that is at 11 to 1.....the ragged edge of pump gas for a carbed engine, again mentioned previously in this thread.
http://www.rocketindustries.com.au/s...es&brand=World
http://www.hotrod.com/techarticles/e...ine/index.html
These guys bypass the 383 altogether and if you want 600 hp they got it, but it takes 454 cubes of small block (again suggest by others) and that is a 10k motor.
here's your 383 with an easy 600 hp, but its blow thru carb.......
http://www.chevyhiperformance.com/te...est/index.html That combo ain't cheap......right arount 10k....
So when I suggest you do homework, I mean do some digging. Put down the Summit and Jegs rags. See what other guys have done to build a similiar engine and what I think you will find is that its a tough nut to crack if you stick to your current parameters.
Chris