Well, I've got a .45 upper for mine. (Not a Colt, they only made 112 of them.)
OK, so I started taking guns apart to do your research for you.
The upper from my 1991A1 9mm will fit my Ace receiver. It does not work very smoothly so you should be prepared to do some fitting. I would also want to install a .38 Super ejector. I don't think the very long Colt 9mm ejector would fit behind the .22 ejector when you were using it with the original upper; but a Super ejector will normally kick out the 9s ok.
