FWIW, this is what I think i have learned in this area, sources are Sheldon, Bikeforums, searchs, velobase and manual examination

I am looking because I was given a Torpado with an ofmega crank, nicely pantoed that I am trying to get working again after years sitting unprotected outside.

The first lesson is this whole area is is murky at best, so these could have some error, but I believe to be as correct as I can find

Older ofmegas had a proprietary spindle/taper. The definition of older is unclear

Newer Ofmegas, essentially the Campy clones. have ISO/Campy taper. This would be early 80's for sure

They need a +5 spindle, like a campy (meaning the driveside is 5 mm longer than the non drive side) clear to see in velobase

Spindle length is very fuzzy 115 - 118 as bet I can determine.

The bike i am fiddling with came with a shimano replacement BB....115 spindle and JIS. Looking at where the spindle bottoms out in the crank, I can see what looks to e be very close to the 4.5 mm that sheldon lists. This concerns me as I am a clyce and I don't like the idea of a non fully engaged spindle/crank interface.

Lessons: Free bikes are rarely that. If your cranks has a matching BB, keep it close and treat it nice, replacing it is way more difficult than you would guess.