mid 80's 318 mpg economy numbers...

I had a dial your own mpgs combo once, called Double overdrive. She could go down to a final-drive ratio of 1.57. That would make 65=1269rpm. Yeah my stock 1973;freshened only,low-C teener (with a TQ and headers) pulled it lol. But that teener still couldn't match the mpgs my 10.9Scr-360 made with a final drive ratio of 2.02.
Those low compression engines have such a hard time pulling good numbers.You can only lean 'em out so far and then they become hard to drive. Reduced rpm is the way to go. I suppose that's why the 2.45 rears and 2.74 lows were invented. This starter is the same as a 2.76 x 2.45. but the hiway cruise is reduced to 89%. So 65 can be 2100 instead of 2370. It's only 270 rpm, but it seems to really count.
The biggest deal would be to have a 4 speed auto in a 904 sized case. Or really the factory shoulda given the A500 it's own diminished-size OD unit.But I guess the retro guys were on vacation the day it coulda made a difference,lol.