I have a 1947 LC Smith 12 Field Grade.
The info I've gleaned indicates it is safest to shoot with a 3 dram or less load. this seems to be around 1200 fps loads.
Also, the info I've gleaned strongly recommends avoiding steel shot, as the barrel wasn't designed for it. There was no concern about the barrel exploding, but that the forcing cone or choke area would get deformed and it could affect patterning, and the force might cause the rib to separate from the barrels from vibration [not something I think is likely though]
I like to stick with 2 3/4 dram equivalents, or less.
That would be something like a 1 1/8 load [7 or 8 shot] around 1145fps, or a 1oz load moving around 1180fps.
The issue of a 3 1/4 dram or 3 1/2 dram equivalent wasn't so much about the barrel/breech not holding up, but that the force could crack the thin neck area of the stock, requiring stock repairs.
I have others for kick butt rounds [870 express Super Magnum for 3 1/2 inch shells], so I'd rather keep the loads lite and keep the gun for a LONG time.
Due to all of this, I agree with the above people and say to stick to #3 ammo on your list.