You should probably approach Hodgdon, which makes Pyrodex, with that issue. The farther you get from the original black powder (BP) loads for which the old revolver was manufactured, the farther you go into "uncharted territory" regarding safe internal ballistics for shooting these old revolvers. (I've got a bunch of them, and determining safe smokeless powder loads duplicating BP ballistics is always a conundrum.)
If Hodgdon says it's O.K. and they have published Pyrodex loads for your revolver's cartridge (on their website --- check for this first, or in a manual --- you will have to buy this), then you've got it. If they don't list loads on their website that you need, or you don't want to spend the money on their manual, ask for specific load data when you inquire about the usability of Pyrodex for your item. I'm not into Pyrodex, but I BELIEVE that the standard procedure is, USING THE CORRECT GRANULATION, you use an equal volume of Pyrodex for the same volume of BP. This assumes, of course, that as a reloader you have a powder scale and can weigh out the BP loads of the original ammo and can convert The volumes of those loads to Pyrodex loads.