45-70 cast loads for deer

[Ruger UL]

I have 2 molds, one an old Lyman 457191 which casts a bullet a bit less than 300 grains and a RCBS 45-405 which casts a bullet around 420 grains. Both are flat nosed with the RCBS mold being the bigger flat nose. My hunting will mostly be in hardwood river bottoms where I might be able to see 125 yards in some places. The rifle is an early Encore Pro Hunter and it is pretty light. Scoped with a 4 power Weaver it still is pretty light. So My guess as to a velocity to shoot for and not get beat up too much is around 1400 fps with either bullet. Anyone have any idea how much of the powders I have are needed to get right at 1400 fps. IMR 4227, Unique, Blue Dot, IMR 4198. I have shot jacketed bullets using the 4227 and they did pretty good, the 300 grain bullets not hitting me too hard using up to 36 grains of it. Anyone here with experience killing deer with cast bullets at that velocity?