Haha almost funny.. I remember shooting my 94AE trapper with 200gr "flying Ashtrays" loaded to the gills over 2400, definitely a max load, and I was almost hitting the bottoms of the vertical concrete berms at the 200yd range. Even at +P+ velocities, you could see the boolits going downrange in a trajectory that reminded me more of turning on a garden hose. We are talking FEET of boolit drop at 200yds.
Not saying it can't be done, but if you and he were to set out a steel deer target at 200yds and see how hard it is to hit it in the kill zone with that Henry rifle, I think he would rethink the distance at which that rifle is effective, at least in that caliber, regardless of boolit style or weight.