old sugino square taper bb replacement?
I have a pitted square taper "sugino mw 68" 114mm long asymmetric spindle (+3mm on the drive side) with a super mighty crank. I was thinking of trying a cheap shimano cartridge unit as a replacement and was wondering if anyone had any advice on which length might be close. I noticed that a cheaper un26? (113, 117.5mm) seems to come in different likely lengths than the un54? (115, 118mm) and don't know if either are symmetric or not. The inner chainring is close enough to the chainstay that I'm worried about getting the shorter lengths if they are symmetric, but also don't want to put things out of balance or widen any more than necessary.
I tried to search about iso and jis but only got more confused, at least regarding this particular spindle and crank. I'm assuming jis (shimano) spindle is ok. Even if the cranks are more like iso, my understanding is that they would just sit a little farther out on a jis spindle, so I'm mainly wondering about the asymmetric measurement.
Thanks for any advice or experience. I'm not looking to spend much and was also wondering about trying to grind and polish out the pits in the spindle races.