Overdrive solution?
with a gear vendors and a 4:10 gear it is like having a 3:20 gear
with a 518 trans a 4:10 would be like having a 2:80 gear
a TKO600 5speed would be like having a 2:60 gear
and i know the keissler auto OD has a low first gear and more OD not sure on the actual ratios.