My '71 Scamp 5.9 magnum swap.

I beileve he see's the LU up as close to effecicent as possible with the 2.94 gear set for the best mileage possible on the Hwy. While the OD tyrans and 3.55's deliver a 2.4495 ratrio.
This is .69 overdrive right?
4.30 X .69 = 2.967
4.10 X .69 = 2.829
3.73 X .69 = 2.57
3.55 X .69 = 2.44

With these know factors, one can choose the best ratio with an overdrive for there purposes. Considering he has a 3 speed with a 1-1 final drive ratio, cruiseing the Hwy. can just simply be what ever ratio is chosen and the RPM @ cruise will only be effected by tire diameter. The LU just helps a little bit here on cruise.

Cool to know the internal pressure regulator up to '96. What is the pressure regulated at?
3.23 X .69 = 2.2287