You would need a ported source for the distributor, constant for a pcv valve, constant for power brakes, and constant for transmission modulator if automatic.
go to chevythunder.com, they have exactly what you are looking for
Check all vacuum lines.
It's lean. Could be a lot of reasons why. Start with the vacuum lines, then the timing, carb, fuel pump, intake gaskets, etc. Look for anything worn or leaking and fix it.
Chevy 350 is just what we call that motor because Chevy is the most popular of the gm lines, but really its a GM 350. Having said that, a Buick, Pontiac, Chevy, or Oldsmobile motor are the same motor for the most part. There are som exceptions with the Cadillac motors but that's an other story. should be smoothe sailing for you.
Could be a lean condition. Check all vacuum lines.
i know one hooks to the brake booster on chevrolet's and toyota's. just follow it from there.
yes the 4.3L vortech has the same motor mounts as the 350
If the Buick 305 is really a Chevy 305, then the motor mounts will interchange with a Chevy 350.
yes.
check for vacuum leaks
No, they will not.
That usually means it's lean. Check all vacuum lines and gaskets for leaks.