Howdy
I'm gonna let you in on a little secret. I have no idea exactly where my Black Powder, 250 grain, 45 Colt loads print.
Way back about 20 years ago I did go to the range and shoot up some targets with my 250 grain Smokeless loads. I even filed down the front sight on one of my Ruger Vaqueros at that time so the bullets would impact the at the point of aim. That Ruger is the only revolver I have ever filed down the sights on, and I have lots of single action revolvers.
I really don't care exactly where my Black Powder loads are hitting because I only use them for CAS. I simply aim at the center of the target and pull the trigger. If I don't jerk the pistol, they hit the target and that's all I care about. Way too much trouble to go to the range and shoot up some targets with my BP loads, just to find out exactly where they are printing. Plus, I don't want to 'waste' any of my cartridges, they take too much time and trouble to make, so they are all reserved for matches. Did I mention that I don't much like cleaning my guns after they have been fired with Black Powder? Another reason I don't go to the range and 'sight in' my Colts.
I can tell you that all Smith and Wesson Top Breaks, such as this New Model Number Three, tend to shoot high because the front sights are so low. I always have to remember to hold low on the target or I may shoot right over it.
So my advice to you is don't change a thing.
Figure out where your loads are hitting, then compensate by holding low.