If you can find a UN72 in a known-proper spindle length... that's maybe an issue because you have to either figure out (or test-fit-verify) the mis-match what with JIS vs ~ISO spindle taper, and with the UN72 likely having no spindle offset in the length needed for your Zeus cranks.

In my case, I had experience using JIS spindles with ~ISO cranks, so I knew what length I was likely to get good clearance and chainline. So I had little to risk in terms of possibly damaging the threads on the now-rare UN72 bottom bracket.
It also worked out well because I had the right tools needed to get the cups fully settled/bottomed in the bb shell (it's been good for 12 years now).

Buying swiss-threaded parts is easier and doesn't cost all that much versus the labor involved.
But you still need to calculate what spindle length of (likely) zero-offset bottom bracket cartridge to buy. I'm guessing 113mm would very likely give more than the minimum needed clearance at the chainstay and provide good chainline if your freewheel sits close to the driveside dropout as it should. A cup spacer can be added later if it doesn't, or the cups may be of the floating/flangeless type and so readily adjustable for chainline.