Sorry I was "off-list" for the early part of your dilema. Glad you got it fixed. What you got is a Rochester 220 TBI system. Probably with a type 747 ECM. One of the easiest fuel injection systems in the world to work on.
I'd suggest engine swapping to a 350/383/400 SBC, keeping the same fuel injection system if you want to hot rod it a bit. Otherwise, you can just keep running TBI on the 4.3L and learn to mess with the ECM'* code if you have a mind to.
Suggestion on rims... Jegs/Summit aluminum 15x8 rims (low buck, very low key, era correct, hot rod goodies) and some BFG Comp T/A tires. Sortta a Buick drag car with Pontiac badges