To the OP's original questions, I switched over to 12v years ago and never looked back. Yes, still using the original 6v foot stomper starter which cranks over fast. This is with an early 60's 235.

I do agree with others about keeping a GMC motor in a GMC.

Craig

My '50 Chevy 3100 5 window, '62-235cu, 3:55 rear
My truck ....... Respect The Rust
If I'm not working on my truck, '65 m00stang or VW camper, I'm fishing with the wife or smoking Salmon.