Sure will,they differ only in barrel and magazine.
Oops,posted early.A 9/38 upper will work on a 45 frame often if you change out the ejector and slidestop,but not always because of the 45's wider feed ramp.
If you do convert it,the barrel will need fit unless it's a drop in.I wold go with a gunsmith fit for 2 reasons:
1.The barrel needs fit and properly.If a dropin is a bad fit,it can batter or peen the slide lugs,which isn't good.
2.Colt 9s (and Supers) are getting harder to find with time.While the 70 series isn't high on the collector's lists,they are only going to go up in price with time.Nice pre 70 and National Matches are pretty much gone,and rotate amoung collectors or get bought up quick if found,so the 50/60s area and 70 series are next up.A well fit barrel and bushing will do nothing unless you shoot it enough to crack the dustcover or slide at the spring tunnel,but that would take alot more than most people ever shoot.A poorly fit barrel could affect the gun,if it's a nice specimen it would be a shame to hurt it.That's just my view but I would definately buy it,it's condition would dictate if I baby it or it's just a tool.
If it still has the fingered collet bushing,keep it for that slide and barrel only.They are a pain to fit and they have been known to break if not fit right,so just fit a new bushing for the new barrel.Trying to replace a collet bushing is no easy feat,they are quite hard to find to stay original.