Bullseye will produce low-velocity, low-recoil loads in the .357. It's not quite as good, loaded-up, as some slower powders (Bullseye is among the fastest-burning powders on the market). That's not a bad thing--sometimes you just want an accurate, low-recoil load.

Power Pistol, on the other hand, is just a bit slower than Unique, and should deliver the Magnum velocities you want.

PS--Around here, we get the infamous "notebook on the counter" with all of the powders and sizes they do/don't have. Mostly don't. I can't touch Vihtavouri powders locally, and haven't seen a lot of what's common elsewhere. Funnily-enough, though, all of the powders I see people complaining about not being able to get, are spilling off the shelves in my neck of the woods.