I'm one of those ones that have been loading up the 45 Colt to it's modern potential since the late 1980's. I've owned and done load testing with several models from Ruger, S&W and Winchester and have 5 or 6 pages of test data collected in my notebook.
Some of the stand out powders in the 45 Colt, in my testing, have been, (in no particular order) Blue Dot, Lil'Gun, 2400, #9, 296/H110, H4227 & 800X.
I prefer cast lead bullets with flat noses and some of the stand out choices have been, (again, in no particular order) Kieth SWC in 270gr & 310gr, LBT WFN 280gr & 300 gr. The best jacketed bullets I've ever tested are the 250gr XTP from Hornady and the Speer 260 gr JHP.
In the past, I've loaded the 45 Colt up to "Ruger levels" but I discovered those guns can take more punishment than I can and for the last 25 years or so, rarely load above the accepted S&W max loads in the 21,000 K range.
In various S&W revolvers, I've gotten 300 gr cast bullets to 1000 f.p.s. (6" barrels) but only with 2400, #9, Lil'Gun and H4227, with outstanding accuracy with #9 when used with a filler like Puf-Lon or Darcon. (Just about all the fine grain Ball powders are position sensitive with some showing over a 200 f.p.s. ES depending on where the powder is in the case.) However, It's very temp sensitive and loses over 100 f.p.s. when the temps drop below freezing. (even when lit with magnum primers)
Lil'Gun is one of my favorite powders in the 45 Colt but it's fallen out of favor with reports of forcing cone erosion in the 454 Casull so, lately I've been experimenting with BE-86, Power Pistol & Longshot. Longshot is promising with the 300 gr bullets but I only just started testing and it's still to early to make a judgement.
Hope this helps.
Jeff