I can remember the 2 3/4" "Baby Magnum" coming on the market. As I recall inthose dys the dram equivelent was not marked on them they simply said Max. The 3 3/4DE*1oz load listed @ 1330 FPS & the Max-1oz load was around 1300 FPS as I recall. I was Young & Foolish at the time so bought a few of them & as long as the gun had "Steel" barrels I would shoot them in it. I did not shoot a lot of them but had no problem with the ones I shot. Some of the guns I shot them from I would definitely not do so today.
Only real concern I would have with a heavier Smith would be the Wood. This not because i=of its reputation but because the wood is old. This would hold true of other older doubles as well, including the Box Locks. I once had a pre 1913 00E Smith with a perfectly sound stock, no cracks that I ever saw & I did look it over closely. This was another gun that had been rode pretty hard.
I don't believe in abusing anything, including guns, but some do carry conservatism to a ridiculous extreme.
