1976 - ish Japanese bike
recent shimano sealed BB cartridge installed was 68x124
same oem crankset reinstalled: supermaxy 52/42T, 171.5mm

Works fine. A little bit on the long side.

I want to go to a 170mm crank. I hope it will make a bit of a difference, shortening the downstroke. The bike is a touch large for me (about 5' 8", 58cm or 23"). Thompson seatpost comes in tomorrow - cant wait.

I determined that the Superbe (or maybe Superbe Pro) are actually ISO (or Campy style square taper), so they are off the list.

The situation appears to leave me with the following JIS crankset options which should slip right on:

Ultegra or 600 model 6400; the only square taper in this line

Dura Ace 7200 or 7400 series

That is a pretty short & not cheap list when those auctions end, and yet there are Campy NOS 170/52/42 or 52/39 cranksets on the cheep...so tempting to try...what other cranksets should I be looking for in a 170 mm length with JIS square taper? Thanks