Richard have you tried any Trail Boss powder? I'm using it in a Ruger #1 450/400 N.E. 30gr of Trail Boss and a 41 cal 200 gr pistol bullet gets me about 1700FPS is very accurate to a little over 100 yards and pleasant to shoot. Plenty of power for a whitetail. I'm also using this in a double rifle and 365gr cast bullets in a 500 B.P.E. also enough for whitetails.
My gunsmith as a Winchester in 45-90 for sale in his shop. I've picked it a time or three. Tempting