I am also pushing the 70 mark and have been shooting SASS (#316) since the mid 1980's. I have just retired from shooting SASS because of problems with my hands working the single action revolvers.
My go to load since Trailboss has came out has been a 200 Gr LRN bullet, 5 grains of Trailboss, WLP primer and either 45 Colt or 45 Schofield brass.
This load has worked well in my USFA and Colt 45's with either a 4 3/4 inch or 5 1/2 barrels It also feeds in my Marlin 1894 45 Colt rifle.
USMC 1961-1971 Retired
NRA Life member and Instructor
SASS LM 316