Since we're just hashing things up: I'd bet you could install 2 BSC (both RH thread) *adjustable* side cups in your FR BB with only minor swearing and no machine shop visit required. You WOULD need one of the Shimano units with both removable cups and 2 of the *alloy* cups would be best (avoid the plastic cups) since you would be doing some forced minor deformation of the threads. This would allow you to select whatever size spindles Shimano made of those UN-73s(?), and then you can fit a modern-ish JIS crank as well...otherwise it's a lot of fussing and cobbling if you have good FR cups and a crank/spindle that fits, already.