Re: 302, the best setup
Vacuum seconday is vaccum from the inlet manifold.
the amount of petrol being injected is the amount being injected, twins look good, but are really only used as big carbies cost more, and sometimes people outgrow the amount a single carby can be jetted to for delievery of fuel.
Keep it simple single carb, rebuilt, jetted correctly, and tuned nicely is all you want, maybe a spacer plate for a bit of accelration down the carby works well though.
I did put something here, but it vanshied, I think
"So long and thanks for all the fish!"