[lippy]

I recently made this choice for my build and went with a TKO-600 with a 0.82 final drive, and a 3.54 rear. The engine will be a 427/482 built to about 600 HP. I found that this exercise was sort of a multivariate equation (excuse my engineering geekiness) between (1) highway noise/exhaust choice/cruising RPM, (2) how the engine is built (cam choice among other things), and (3) driveability (e.g., drop off between gears, tractability, etc). Brent will be building my engine and he was helpful here. In the end we decided that if I want a higher HP build that necessitates a hotter cam, cruising at highway speeds with the 0.64/3.54 combo would be challenging. With that gear combo, a milder engine that is happier at low RPMs is better. The other factor is that, with a 0.64 trans, the drop off between 4th (1.0) and 5th (0.64) is big and would require more 4th gear driving, as pointed out by CSX4017 above.