I've heard a number of horror stories about the threads galling badly on Ruger stainless. I've never tried it myself, so can't say anything from either side of the fence.
Either without that, I'd be more inclined to sell the spare barrel, and pay someone to cut and crown what you've got. If your current barrel had problems, I'd go for replacing. So, if you're happy with the accuracy, your barrel-cylinder gap, and whatever else you can think of, just get it trimmed back.
The biggest issue I've heard from local gunsmiths is the fact that they prefer to put the barrel-frame assembly into the lathe, which requires an appropriate counterbalance to do. There are mostly rifle smiths around here, so revolver work is tough to get done. On the other side of that, you can probably do some internet digging and find tutorials from guys that have done it in their garage with a hacksaw, a drill, and a few files.
But still, I'd probably opt for cutting, unless there were other issues.