There isn't a whole lot of variation in pressure curves, even from black powder to nitro--although that old wives' tale was around for a long time. The Dupont graph from the 30's showed it wasn't true then, and Sherman Bell's pressure tests showed it isn't true now. Pressure drops quite quickly past the peak, which is always reached in the chamber. There is variation from one powder to another, but not really enough to be concerned with as far as danger from a pressure burst is concerned.
If you're looking for factory shells that are safe to shoot in vintage guns (assuming said gun is in good condition), you're in pretty safe territory if you go with shells designed for CIP "standard proof" guns. Most of those seen in the States are field loads rather than target loads, so you can reduce both pressure and recoil even more via reloading. Or you can go with shells from an outfit like RST, which will provide you with pressure figures.
