Somewhere in a thread I posted about the Model 60 several months ago a forum member posted a S&W table showing some of the older Smiths and acceptable cartridges. I'll see if i can find it and re-post.
The early J-Frames were not rated by S&W to take +P ammo. A lot of people use it. The "general" consensus is to treat it the same way you do K-Frame .357s, a lot of .38Spl, and little of .357. So, a lot of .38Spl, and a little of .38Spl+P.
I do know that when I was a AFOSI Special Agent in the USAF, we had 3" Model 36s. And, a lot of them failed due to the number of rounds of military hardball that we put through them. Military hardball, at that time, was notorious for its inconsistency. Some rounds were so weak that you weren't sure the bullet even made out of the barrel. Others felt like magnum rounds. AFOSI finally scrapped the lot due to the frame stretching and cylinder bulging and cracks that appeared over time. Granted, we probably put more ammo through a 36 in a year than most people probably do in a lifetime.
Hey, it's your gun! But, if I were you, I'd keep the +P stuff at a minimum.
Don't know about all +P concoctions out there but my J-Frame .38 Specials have been fine with the +P 158 grain lead SWCs. It's not a loading that I find myself enthused to shoot in large quantities anyway.