I musta missed the original post, but caught it on Digest just now.

  I don't have a re-geared tranny, but I do have a 5 speed, I guess from a diesel, that's hooked into a 1.8 liter Cabriolet motor.  It has a mild cam and an aftermarket muffler, but otherwise,  it is stock.   With that tranny and standard size tires, it actually feels pretty good at around 70-75mph.At about 80mph, the motor sounds sweeet, but driving a shoebox at 80, with it's just adequate brakes and high center of gravity..not my style....Under that speed,60-65,  and it is coming off the powerband of the little 4 banger.  I shift down to 4th at around 60, if I am trying to accelerate or going up a grade..From there, it'll go right back to about 75(in 4th) before it is feeling wound out, but that is too high to rev it and have it live long, I guess.  You can get another motor for about $300 bucks, I am told, so no real worries, but still..
  I will probably look for some 15" wheels and larger tires, to make the gearing even taller, and then use 5th gear as more of an "overdrive" for easy highway cruising..I really do like having the extra low 1st gear, which I use only on very steep terrain..usually, I start in 2nd. 
  Not what you asked, but another idea perhaps.
  Don Hanson