I don't know what the differences are between modify and rebuilding. I had planned to ask Cliff for a good recipe for my engine specs and start from there. I assume somethings would change and modify some others to work on todays gas. Is that modifying? if so, can you elaborate why the two would not be good to modifying?
I chose these two because they resemble what I current have in looks. I have a 68 7028271 carb for my 68 Firebird 400 HO. Cliff rebuilt it and set it up for my engine specs. So I was wanting to duplicate it and perhaps trying different things and what it does to either make it better or worse. Just learning how they work and tune and adjust after that.