Sounds like a good deal on what is probably a good solid hunting rifle. The T/C Hawken guns usually came with a 1:48 twist barrel, meaning you could shoot patched ball or lead conical bullets and get good accuracy with either. Get the factory manual for load info, it's a good palce to start. I have a T/C Pennsylvania Hunter model (.50 cal.), it shoots patched ball very well with a load of 3FG balckpowder. For a hunting load, depending on your states regulations, I would try one of the Hornady Great Plains Bullets over a recomended charge of 3F, and see how it shoots. In my opinion the .45 cal. ball is a little on the lite side, but I like heavier bullets, and it is just my opinion.
Go for it! It'll be fun.