I cast and shoot 454 Casull in a Rossi R92. I have a few different molds I use, from 290gr to 350gr being the heaviest.
I use a Lyman 454647, a 285gr truncated cone gas check mold that is about 295 checked and lubed from water dropped wheel weights. Shoots great with no leading sized to .452" with Hornady checks and Speed Green lube over 28.5gr of Lil Gun. No idea of velocity.
I shoot the Lee C452-300-RF sized and checked as above weighing about 325gr over the same charge with the same no leading results and slightly more recoil. No signs of excess pressure.
I will shoot a NOE 454651 which I purchased from a group buy on Cast Boolits. It was supposed to be a 325gr boolit dropped from wheel weights but it came stamped as 350gr. When I contacted Al at NOE he told me it was just stamped wrong. Well, sized and checked from a copper enriched water dropped wheel weight alloy with 666-1 lube and Hornady copper checks it is about 353gr. I have not had a chance to shoot these yet but have very high hopes! They will be the first real test of my copper enriched alloy as well although I have had good luck so far with it in the small bit of testing I have done with 9mm in my CX4 (Lee 356-95-RF / 4.2gr 700x and tumbled in Recluse lube). I have thought about sizing a few different 45-70 boolits down to .452" but as of yet have not exhausted my testing of the boolits listed above. I also shoot the first to listed boolits from my 45 Colt lever guns (20" R92 and Ranch Hand) as well with great results over stiff charges of Lil Gun.
If you're looking for heavier than that, I would suggest sizing down .458" boolits. Works quite well. I've sized a few Ranch Dog 360gr. .458" boolits down just to see how it will work and they sized fine. Best results were dip lubing and then sizing so the microbands don't disappear. Not a problem with standard lube groove boolits though.