The two biggest mistakes some engine builders make is "too much cam" and "too much carburetor". Either one alone will make for difficult low speed operation. Put them together, and it's the stuff nightmares are made of. At 6K RPM, a 383 is flowing less than 600 CFM in real world numbers, so virtually every carburetor the hotrod shops recommend is WAY too much.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!