You should be able to find either length without a lot of dough... either way, the longer spindle is ok, the BB shell width is prolly more important, assume yours is 68mm. BB's are very common setup for 73mm shell and use a spacer for 68mm shell. I may have a spare octolink BB... and am pretty sure I don't have any octolink cranks anymore. I'll check.

For sure you can use new external bearings/cranksets.

Rg.