The 44 Henry had a 200 grain bullet, .445" diameter, with 28 grains of black powder. When I had the .45 Colt Henry, I used .45 Schofield, a 200 grain .452" bullet, and 28 grains of BP. It is .007" lager, while a .44 Special with a .429" bullet is .015" smaller. It was an exact duplicate, down to the 1130 fps I was getting from the Henry.
The only reason I swapped the .45 henry for .44-40 Henry was blow back with the .45 Schofield case in a .45 Colt chamber was awful. I had to squirt the lifter every other stage. Even with Trail Boss, it was sticking by the forth or fifth stage due to blow back. If it had a .45 Schofield chamber, the blow back would be much less, especially if I annealed the case mouths.
Right now, for my Henry, I shoot .44-40 with a 200 grain bullet, and 7.0 grains Trail Boss which gives me about 1130-1150 FPS. At the Railroad Flat night time BP side match, I shot 30+ rounds of .44-40 loaded with BP and had NO problems.In my 1866 which is in .38-40, I shoot a 180 grain bullet with 6.5 grains TB, for about the same velocity.