What's the point in installing a different 4 speed with the same 1:1 top gear ratio? There are lots of original transmissions available, plus a bunch of full-synchro passenger car 4-speed transmissions like the Muncie or Saginaw if you want to use all 4 gears without double-clutching or coming to a full stop to engage 1st. gear.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!