Your new pro Hunter
First lets look at mount options. There are several mounting options available to you using the standard weaver style rings or similar slot type rings such as Weaver, millet,Warne, etc. If you decide to retain the sights on your rifle may I suggest the leopold QR (quick release) system.
This mount option requires the leopold quick release base and rings. The rings have a lever on them, just insert the rings in to the base and turn the levers down and the scope is LOCKED. If you desire or need to use you sights just turn the levers up lift the scope off and the sights are available to you. You can remount the scope with little or no change in zero.
This mount system runs about $60.00
As far as scopes, you have to many options and prices. Buy the best scope you can afford. A 3X-9X is more than ample for a black powder rifle. If you opt for a leopold scope the VX-II series in my opinion has the better click adjustments than the VX-1 series. And of course you pay for this difference in click adjustment options.
As far as loads, purchase the T/C 250 grain shock wave and a pound of
777 loose powder in 2f and some primers. Start measuring you powder
at 95 grains working up in 5 grain incrememnts. The T/C clear view
powder measurer in calibrated in 5 grain increments. Some where
between 95 grains and 115 grains of 777 loose powder you SHOULD
find an accuracy load.
You can also use some 50 gr pellets to get your rifle on paper and try them as well.
Be sure to clean in-between shots with a spit patch (mouth wet) and you should generally clean after a 3 shot group and be sure to dry your barrel.
Good luck....