This is probably the most civil 307 thread I have ever read.
I opted to use an old, unrebuilt, early 70s 307 in my 66 elky.
All I did was put a q-jet and intake manifold on it.
The car has a 5-speed (TKO 2.87 first) and is plenty peppy even with the 3.08 rear gears.
And gets better than 25mpg on the hiway to boot.