I've done a couple. It's an interesting project. Couple things to watch for; Serial number positioning on the butt and thickness of the front strap, especially where the strain screw goes in. I've not done an early N-frame so I don't have a good mental frame of reference for the above concerns.
On the ones I did, one was a later production gun with extra material in the front strap, so when I cut/ground to round butt size, I just had to deepen the recess for the strain screw head. The other was an early 70s gun with a thinner front strap. After some head scratching, I cut the front strap just above the solid part of the butt, heated & massaged it back, tacked it, clearanced on the inside for the mainspring, and finish welded it. Otherwise, the strain screw head would have to have been removed & a slot cut in the threaded shank for install/remove. Not a real good idea as the shoulder of the head bearing on the frame tensions the screw to keep it from backing out from vibration. A set screw should be fitted to bear on the strain screw if you decide to go this route. The same cosiderations for the back strap. If it's thick enough & you won't get into the serial number, grind away. If necessary treat as I described the front. I've got a nice 25-5 4" round butt sitting next to me as I type this. Best thing I could have done to it.
