Words of encouragement! Planning on a 4 barrel nikki... going junkyarding saturday!
I think a 4 bbl would be way too big.
A supercharger can create plenty of intake manifold vacuum under the carb, so a huge carb is not really necessary.
At low/mid speeds your airflow would be too low to push fuel UP to the intake manifold.
Atomize better with a smaller carb, let the supercharger pull the air thru at high rpm.
My 2 cents.. Start with the STOCK carb, just bump fuel pressure up a few psi.
If your top end is weak, then upgrade.