You can also install the Bisley hammer in a NM Blackhawk by "enlongating" the slot for the hammer, towards the rear. This give ( to my eyes, anyway ) a neat look. Looking at it from the side, you have the "humps" where the grip frame flares up to meet the frame, then to the rear there is the now-exposed part of the rounded portion of the now-exposed base of the hammer, if that makes sense.
Gives it a different look, I think the early Remingtons, or some other revolver, had a similar look. No way can I post pic's, hopefully someone else can.
Mark