i have a shimano 600 component group i got off a junked c.itoh. it has a nice BB that belongs with the 600 cranks, but it seems to be 73mm. ive never come across a 70's road bike frame with this BB shell size. the strange thing is that the BB spindle says 68mm on it!!! can i use this BB with a spacer on a 68mm BB shell? or should i just buy a sealed unit? when examining the spindle compared to other spindles, it seems that the raised portion of the spindle which the bearings rest on are spaced further apart than the usual BB spindle, giving me problems with the normal BB shells. any recommendations?