jorb,
The shifting mph will change with the 3.55, but I am not worried about this. As Greg posted, Bill Miles has a 3.55 set up that works fine.
I think you probably know that the first to second-gear shift takes place anywhere from 3mph to 8mph. After following instructions for from Greg and Bill, I got my 3.90 rear Hydra-Matic to up-shift and down-shift nicely (a 1/16th rotation of the throttle-rod pivot produces a large difference in shifting-point mph). I have no worry about getting it right with the 3.55 rear-end through slow and careful trial-and-error adjustments.
