I believe I know what gun you are buying, and I'm glad you are, it will prevent me from spending the money!
I have a later gun (approx 1940's) 3" chambered, 1 1/2" oz load marked. However, it is also marked with the 3 1/2 ton designation. While your earlier gun does not carry the proof marked in "tons" the 1 1/2 oz marking should put it in that same category. The advice to keep pressures within 2 3/4" limitations is sound. Keep your loads under 10,000 psi.
And please post some pics when you get it!
