The Fiocchi 455 MKII's are not very hot loads. It says 850 FPS on the box but in my experience they usually measure ~700 FPS muzzle velocity on the chrono.
455 mk II rounds should chamber into the .450 adams, but the tolerances might be a little tight. I would personally use slightly lighter smokeless loads to be on the safe side seeing as they are blackpowder guns.
If I had an Adams chambered revolver, it would be relegated to wall hanger status or fired with BP - only!