Bought my Ruger Blackhawk .45 in 1973. I used to shoot it a great deal in the 1970s, not so much anymore.
My favorite load was the Keith cast semiwadcutter 454424 of 255 grs. over 8 grains of Unique.
I don't have much experience with 230 gr. bullets, but heed this warning about Unique powder:
One day out camping, after the pistol and ammo sat in the car trunk all day in 15 degree weather, I dragged them out for some plinking.
Shooting at a can on a stump, my bullets were hitting over, under and wayyyyy under the can.
Later, I learned that relatively small charges of Unique in large cases ignited or burned poorly. Switching to Magnum primers cured the problem.

If I figure that my loads with Unique might get cold, I'll use Magnum primers. Otherwise, for standard "fair weather" loads I'll use regular primers without a problem.
I don't much care for heavy loads in the .45 Ruger. I have a Smith & Wesson .44 Magnum for that.
A 255 gr. slug at 900 fps is still a fearsome beast. Not much point in my using heavy loads, just to put holes in paper and cans. But, if need be, it will still anchor any man or beast in North America.