The S&W 500 grips will fit on a round butt N-Frame. Oh my goodness I took it to the range today and I could not believe it. Shooting factory remington 240 gr was like shooting 44 specials. I then shot some of my own reloads of 18gr of 2400 under a 240gr Jacketed soft point. I put all shoots at 15 yards in a 1 3/4in group, they were all touching. I am just so excited about this. Those grips made all the difference for me. The original grips leave the back strap exposed.
Now for a blued weapon like what you have in a model 29 I wouldn't dare put rubber on them, all blued weapons deserve wood grips. But if you are set at putting on rubber grips leave pachmeyer alone and get the S&W 500 it really tames the 44 magnum. But again they will only fit on a N frame round butt.