Just recently got my dad's 68 Cutlass back on the road, question. What fuel grade should I run in it and what fuel additive? Lead substitute? 350 Rocket 2 bbl. auto.

 

Your 350 2bbl motor only has 9:1 compression and should run just fine on regular. As for additives, the reality is that for an infrequently driven car, I wouldn't bother. There's plenty of lead built up on the valves from years of driving, and using unleaded probably means that you'll only go 80,000 miles before you need a valve job instead of 100,000 miles.