After posting, I thought about it some more, and, I changed my mind but had not got back to the Thread to discuss some more.
Yes, on a modern 'Conversion' there's no reason to stay with BP or subs ).
The only loading/re-Loading I have done in .45 Colt, has been with BP, Duplex, or Unique...or '777'.
All of which work very well.
Have not tried Universal.
But, I gather, .45 Colt is one which quite a few various Propellants can work very well with.
Post some images of the Revolver!