As far as velocity, I have no idea. I'll give you my hunting load that was used:
300gr Hornay HP
38.0 grains of H4198
Winchester Mag primer
Winchester brass
Holdover??? Well that was with the rear sight in the tallest notch, and using the front sight base about 2/3 of the way down it.
How's that for scientific?
Now, to be fair, this was the third shot on the buck. He just stood there and let me walk them into him. I shoot a 45/70 quite a bit, so holdover for me isn't too hard. I'm talking 100 rounds in a weekend when I shoot. No BS. But that is with a different gun/load (Trapdoor/45/70), but still the same principles.