I would limit trans choices to either stock converter 904 or either 903/230 3 speeds.
Any gear ratio in that 7.25 you want, as long as it was factory available.
4 speeds were a factory option with a Slant in 64-66. Hopefully it won't be that selective when it comes to factory parts.
Fastest car wins the prize? What happens if a guy drives several hundred miles with 2.94s and another trailers his with 4.10s?
Sounds like it should be bracket racing with a few classes based on mods.