some information on the justy is on this Wikipedia page:
Subaru Justy - Wikipedia, the free encyclopedia
using those numbers with the stock tire size puts 60mph at about 3600 rpm with the second gen transmission and 3400 with the first gen transmission
(
Subaru Justy Forum - Manual Gearbox Teardown/Interchange )
the place that pointed me to the site on using the second gear as a replacement 5th noted a drop from .675 to .590 which would get me to about 3150rpm at 60mph.
I would love to get that number down by another 500rpm at least. My plan is to go all out with mods. Including a boat tail, wheel skirts, undertray....