If I were you I would register at hotrodders.com, and find a guy named "Tech @ BG" -- he is a helpful guy and will recommend a carb for you. The phone service at BG is notoriously lousy and rude, but this guy is an exception but I don't know his phone #.

For my , with that cam it calls for the mighty demon, and the smallest one they make which is 650 CFM. They flow more than that. For my 440 they recommended the 750 CFM mighty demon, OR the 800 CFM annular discharge since some of the flow is restricted by the larger boosters. I went with the annular, and after 45 minutes taking the carb apart, finishing up the drilling they didn't complete (partially drilled holes in metering blocks), removing small flakes of metal that were hanging ready to come off (in metering blocks and body), then blowing the whole thing out, I'm happy with how it runs.

Count on taking it apart and going through it.. BGs reputation for bad QC is deserved (my carb was bought new a couple months ago, so the QC problems still exist).