I make pb bullets in any weight, diameter or profile asked for.
My recommendation is an LFN, and if you use LBT bullet lube, 1700 fps is a relistic speed, with accuracy and freedom from leading. However the bore MUST be smooth, and few new barrels are smooth enough to stand that speed with PB bullets. Order our lap kit and a pack of 45 rifle push through slugs when you order the mold, and you can lap the barrel quickly till it will perform for sure.
460 diameter gives best accuracy in most Marlins, because it fills the chamber well, which keeps the bullet straight while being driven into the rifling. Some chambers will require sizing to .459, some could handle u[ to 462, but the difference in accuracy doesn't make it worth the effort of doing a chamber slug.