Here's a good link regarding JIS and ISO crank/BB tapers.
https://www.sheldonbrown.com/bbtaper.html
That said, when I was an indigent bicycle racer I put JIS cranks on ISO (Campy) BB spindles by cutting small rectangular pieces of beer cans (Coors of course) and used them as shims on all four sides of the BB spindle. If you played with the length of the shims (held in place during install with grease between the shim & BB spindle) you could adjust the chain line. I also used this trick on worn Campy cranks that would draw down onto the spindle too far. Now days if i were going to do it again (and I would if I needed to) I'd use real shim stock to get it just right.