I was clear on you not wanting an OM hammer. I was just trying to help by throwing-out what I've learned about using the "conversion" trigger in an otherwise "unconverted" OM Blackhawk, which your's is surely going to be. No getting out of that, RP Bisely hammer or not.....because....no matter what, if ya aint using the "conversion" hammer then ya aint going to use the "conversion" latch, transfer bar, nor the "conversion" trigger (as-is)....unless ya figure out a way to fabricate/install a suitable hammer cam to trip the latch, then mill away enough of the after-market hammer so's the transfer bar will work, and then grind the hammer nose to allow the bar to work.
I was also clear on the "no welding" thing. So, the only other option I see is to gather-up the proper OEM (non-conversion) action parts (sans the hammer which you don't want) and fit it all together using the aftermarket (Bisely) hammer. Assuming that the hammer in question is up to spec, that seems to be the easiest course of action.
Hope this helps.
DGW