I would use a 270 to 310 grain traditionally shaped paper wrapped bullet of .450" diameter. 16 lb paper usually works well.
A charge of 110 to 120 grains of Olde Eynsford 1 1/2F with a 3/16" lube cookie will get you close, if not right on the money.

A slight adjustment to the charge or bullet weight will bring the barrels together, if they don't do it right off.

There's no mystery to Henry rifling, shoot papered bullets and you'll do fine.