Well, I'm sure in theory it
could be done, but it would be an awful lot of effort. The back of the cylinder would have to be milled down of course, plus some way to retain the rounds in the chambers would be in order, and the device to do that might then also require the frame itself be somehow modified. Of course, you'd need to find a machinist willing to do this which might not be easy and almost certainly would not be cheap. Depending on where you mounted the firing pin you might also lose shotgun capability if the pin were mounted on the hammer itself. If it were mounted in the cartridge retainer then that might not be an issue, but then I don't know if Krist may well have some sort of patent on such a device which would mean you'd run the risk of a lawsuit if they found out you copied it.
For caliber, I'd be more inclined to go with .45 Schofield. Smaller OAL, meaning lighter load capacity, which is good if the cylinder walls on the LeMat are as thin as I think I remember them being. Still uses the same diameter bullets as .45 LC.
If you're thinking of selling the thing let me know. I might be interested in another one. Shouldn't have sold my first one. All the neat toys always turn up AFTER Christmas!
Cpt. Redleg