3.08 gears are the "kiss of death" for these sixes, a very good rear gear ratio is a 3.55--very well rounded ratio--it will wake up the smallish motor and let it run more freely--if you do this first it may save you a lot of motor hop-up spending--it's really a wake-up move. The original '62 Chevy lls were equipped with 3.55s, then in '63 they switched to 3.08s and performance plummeted. I had a '63, and the '62s would embarrass me. Switched to a 3.55 and wow what a difference--almost like going from a two-speed PowerGlide (1,82 low gear) to a three speed Turbo hydramatic (2.54 low gear)when you hit the "go" pedal---OOOOPS--I see now I came 'waaay too late with my suggestion!!
I don't know what transmissions they were using in the early '60s, but I know the history of the 250 inline in the Camaro and finally made it into a chart:
Assuming they were using the same 2.85 first gear Saginaw 3spd in the early '60s, then for those of us with the later wider 3spd:
Saginaw 3spd std: 2.85std & 3.08 rear = 3.11wide & 2.73 = 3.50superwide & 2.56
Saginaw 3spd perf: 2.85 & 3.36 = 3.11 & 3.08 = 3.50 & 2.73
Sag 3spd hi-perf: 2.85 & 3.55 = 3.11 & 3.36 = 3.50 & 3.08
I don't know how to compare these to the powerglide and TH350, as there is the automatic torque difference? But a 3.08 may be a "kiss of death" for the standard Sag 3spd with its 2.85:1 first gear, but for my setup of '78 3.50:1 first with 2.73 rear it would actually end up being deeper ratio for 1st than the standard Sag with 3.55 rear.
I'm not sure if you can compare the powerglide to the TH350 directly just by the combined ratio. But just doing the math here's how the 1.82 powerglide compares to the 2.52 TH350. Which remembering my second Camaro with a 305cid with a TH350 and open 2.73, does not seem all that hi-po:
auto std: Pglide 1.82 & 3.08 = TH350 2.52 & 2.22(?)
auto perf: Pglide 1.82 & 3.55 = TH350 2.52 & 2.56
