Yes Cookieman, it would be easy to rebarrel for .45 Colt. The only lathe work is to turn down the diameter of the new barrel to fit the monoblock and chamber it. Cut a simple slot for the extractor and re-use the original extractor. However, I'd stick to mild loads since the frame is some sort of non-ferrous alloy, in other words "pot metal". The finish is a thick coat of black paint, probably some sort of baked on epoxy, when chipped or worn it is very hard to get any touch-up paint to adhere.
rlm2007x, I don't mean to discourage you. The Comanche is a fine snake gun, a .410 load of 7 1/2 shot will hold a deadly pattern to 25 feet or so, all you'd ever need for snakes and the .45 Colt would be accurate enough for personal defence on big critters out to fifty feet, again all you'd ever need, but that is about it for the Comanche. In other words, it is an effective gun so long as you get in close.