Just realized I had never updated this.
Talking to Edelbrock, the 800 is what they recommended for the 383 and this use.
In the end, it wasn't a fuel issue at all. Solving it was replacing the points with a pertronix module and replacing the coil.
I think it was likely a bad/failing coil...
I am still playing with building an engine similar for my car. Leave the convertible stock 383. Make the roofie car more fun. Dad always talked about building a stroker motor for the 4 speed car.
I purchased a new wiring harness for my 65 Polara from Evans. Well worth the money spent, if they make one, that is the way I would go and I'm a licensed low voltage tech.