No +P loads in a J-frame. Some folks say they're okay in a recent K-frame, but I'd reserve them for L-frame S&W wheelguns.
Even though the M60 in .357 Mag was introduced in the mid 90's, I'd shy away from the hot loads (especially as a steady diet) given the past problems with the K-frames attributed to stout loads..... the J-frame is even smaller.
I agree with the first part. The old Model 60's were never rated for +P.
I just got a Model 442 which is rated for +P and I intend to shoot it and carry it with +P. I should think this would be safe and has been to date. In this day of lawsuits, if the manufacturer has the nerve to list a gun for +P then it should be okay to shoot at least some +P in it.
+P in my Model 10 is a given for a carry load. It's .357Mag K frame brother gets mostly standard ammo but guards the house with 125gr JHP full Magnum ammo.
I would think that the concern here is that the higher pressure loads will shorten the life of the gun, not blow it up.
Practice light (shoot enough to be competant with the +P loads) and carry heavy and the gun should last.