http://www.4secondsflat.com/Calculator_for_CID.html
I thought 383s were 3.8" stroke with a 4" bore???
You sure you're not building a 377???
Is this drag only, or street/strip? If it's drag only, assuming the head flow info from RHS is correct, I think the cam is to small and compression is too low (estimating 10.5:1 with 64cc head and .050 gasket).
http://www.racingheadservice.com/Inf...-SBC-200cc.gif