Well this happened today.
Welded 3 piece wheels are a pain. Taking a cutting wheel to a 20 year old discontinued rare Japanese wheel is probably the scariest thing I've ever done, but I took my time measuring and cut the weld perfectly in the center to split the barrel and the lip. There's no damage to the barrel, which is what I wanted to re-use. The lip would take some machining to re-use, but nobody has any use for 2.5" 19" lips so it's just a wall ornament now anyway. Next up is to have the face chromed and order a 4.5" lip and new bolts, I really don't want to reuse the old ones.