I once owned a four-inch M-34. I presume that you know this is a blued version of your M-63. I holstered it in a Safariland Model 25 that I bought as-new at a gun show.
The holster was wonderful. I'll never buy another .22 revolver, though. Extraction was a nightmare and a very well known source at S&W admitted that poor extraction has been a problem for decades. I literally had to pound the extractor rod with a shoe or plastic mallet to get ejection. I presume that your gun works better. Personally, I decided that a small .38 makes a lot more sense in that role.
If you can't find a Safariland M-25 or M-29 for that size gun, El Paso Saddlery makes an almost identical item as the Model 29, called Model 2, I think. The workmanship will be excellent, and they may make one for J-frames. Check their site,
www.epsaddlery.com. They also have a basic Threepersons design that looks much like the Bianchi above, but of better quality. My holster was dark tan, with green suede lining and basketweave stamping. It was beautiful. I sold it, as I knew that I'd never again own a S&W J-frame .22. I acquired El Paso holsters for a M-60-4, three-inch full-lugged barrel. If they made those for me, I bet they'd make one for your .22. It'd be a nicer holster than those discussed above.
I'd use a synthetic holster, Cordura, etc., only if operating in a rain forest or cloud forest environment or other very humid areas that'd rot or mildew a leather rig. If you wear the gun at sea, that might warrant a synthetic holster. But I don't think it has the power to shoot sharks or other dangers in the ocean, or pirates.
I do still see a need for a .22 in some roles, but mine is a Ruger MK II auto, stainless, 5.5-inch bull barrel. It's a much better gun than that jamming .22 S&W. Its holster is an old Bianchi M-89, if I recall the model right. I bought it new, years ago. I don't necessarily recommend Bianchi now, but they once made very good holsters, in the USA.