Didn't read the thread well, so you landed on the roundball 54. Good choice (says the die-hard traditionalist).
My wife hunted with a 54 Renegade this past week, elk in NM. No shot at a legal bull, but she spent about five weeks working on the load and her accuracy with a rifle that is a big cannon for a little lady. She used the Lee REAL 380 grain bullet, with 90 grains of 3fg pushing it down range. A Pachmyer slip-on recoil pad, with a PAST pad on her shoulder, made bench work tolerable. Tough to do with the GPR curved buttplate, hopefully you can shoot offhand as much as possible to help with the pain. Just remember that the hawken is designed to be shot with the butt on your ARM (just above the bicep), not your shoulder, with the rifle across your body. Keeps the pointy parts from digging into your chest (ouch).
Enjoy your rifle! I am hoping for a kit for Christmas, I need an elk rifle that isn't a flinter (it actually does rain in NM, usually inconveniently when hunting).