You will also need to keep and eye on the hardness. Most cases this long need to be annealed before their first use and every once in a while thereafter. If you notice a lot of smudging down the sides of the case upon firing it is time to anneal. The longer the cases (larger charges) to more frequently you will have to do this, they work harden fast. If you do not anneal your accuracy will be very disappointing.
I have had no luck with BP substitutes, hopefully you will do better. In 45-110 and 50-90 I get the best groups with Swss 1.5F, matter of fact, I get the best accuracy in all my BP guns with Swiss 1.5 except for the 50-70, 2F seems to work better in it.
I usually tumble all BP casings between firings, this is done after depriming and sizing (tumbling after prevents any lube contamination). I then prime and charge the case through a 30 inch drop tube. The charge is then compressed with a compression die, the amount depends on the powder and previous testing. With some charges using Swiss no compression is required. I then place a hard card wad (milk carton cut with a die punch in the reloading press) on top of the powder charge. I then put in a disc of wax paper (cut with same punch) on top of the card, this prevents the bullet from sticking to the card wad and affecting flight. The bullet is then "thumb-seated" (might require pushing against the edge of the reloading bench) until it is in firm contact with the powder charge/wads. I then use a taper-crimp die to put a little grip on the bullet and ensure consistant bullet release pressure.
SS