When I started loading the 45 Colt, I wanted to keep it simple, seeing I have many different loads for all other calibers I load.
I use the 45-270-SAA (actual weight 283gr.) over 9 gr. of Unique, I used to use the same charge under the 255gr. RNFP also.
The above loads are all I shoot in my 25-5's, Mountain Gun, Blackhawk, Uberti SAA clones and Rossi 16" Trapper carbine.
With those big hunks of lead, I don't see a need for more velocity. It is going to pass right on through