You might want to take the route that I took for converting. I wanted a pair of "blue" OMV in 38/40. I started shooting B/P in SASS. I shot smokeless in 44-40. But everyone knows that if you shoot B/P in guns after shooting smokeless you'll mess them up!! Sooo,, ya have to buy new guns. " THAT'S MY STORY ,,AND I'M STICKING TO IT"
Ruger doesn't/didn't make that animal. So I got a pair of the 38-40/.40SW in SS. They're fine,,,, but this is "me", I don't like "shiny" guns,, nickel, chrome or stainless or any bright gun. I thought of different ways to do the SS OMV's for a couple of years. Nothing came to mind. Then BINGO !.Got a pair of .357 OMV's, blue, cch. pulled barrels off, sent them off to be re-rifled for 38-40,, cylinders the other way for rechambering. Now I've got a pair of blue, cch,5 1/2" bbl 38-40 OMV's. I had the bbls engraved 38WCF, a little Jim Downing here and there annnd all is well in Rugerville. The reason I sent the bbls and cylinders different ways is because, best price for doing the barrels, but he didn't do cylinders. Person that did the cylinders wanted to much to do the bbls.
I'm happy
Isom Dart