I must not have given enough info first time it is a 454 + .080. The dart heads heads seem to have a large stud boss. Plus the stud girdle should help stiff things up. I guess I am glad I brought this up if it should be an area of concern better to head it off now.
Nope. You gave enough info the first time. I SWORE I saw SBC at the beginning, so was thinking small-block this whole time. 1.8s are no biggie on BBC. Sorry, my error.
Back to carbs, with your 471-incher, 500's would be the minimum, I would think. Yes, some of the race motors make big hp with tiny carbs/restrictor plates, but those are also much smaller displacement. Yes, it can be done, but you are talking very high-tech cam profiles, porting, high compression, etc.
My "little" 346 cu in 1957 Ford Y-block (stroked 312) made 18 more hp going from a 500 edelbrock to a 625. The numbers will be exponentially more on a BBC.
My idea of the 390s would be fairly crisp throttle from idle-3500 or so and then it would run out of airflow. Just an idea thrown out there.