I recently saw a Bowen custom Blackhawk with a Bisley hammer. Looked pretty trick to my eyes and I was wondering how easy/hard it would be to do something like that myself. Would it possibly be a drop in?
Don't know why it wouldn't be, if it is designed for the Blackhawk? The only issue you might run into is trigger engagement, and that shouldn't be an issue if what you have now is straight factory. If you've had a trigger job, though, it will likely have to be done over with the hammer change.
You can get a Ron Power (modified) Bisley hammer that will work with the Blackhawk frame. The factory hammer would have to have "excess" material ground off the back hump before it could fit in the smaller frame opening.
If you swap out the grip frame, hammer, and trigger as a group, then it's a drop in.