I think you are proceeding well. I too have old eyes, and with open sights can no longer get the tiny groups I used to. In reality, 3" at 50 yards is adequate for deer hunting, even though we would all like to do better. Recently, I put a peep sight on my Cabelas Hunter Hawken. Never really have cared for this rifle, hadn't shot it in decades, just blah accuracy, no style, and I have rifles I like a lot more. So, since I had nothing to lose, I put a peep sight (Lyman 57) on it for giggles. Fired three shots at 50 yards, got a cloverleaf 4 inches low and 3" left of Bulls-Eye. Clicked it up and right some random amount, next three shots went thru the same hole, literally, in the Bulls-Eye center. Made me a Big Believer in peep sights, and now I really like that rifle! Just got a nice 10 point at 65 yards with it last week, using a 60 grain 3f Swiss load, and a PRB.
Your load of 70 grains of 2f is a good load for deer, if the accuracy is acceptable. With a PRB, you are getting 1500+fps, which will smack a deer right down. More powder in that short barrel will give more recoil, muzzle blast, and less accuracy, but very little if any more fps. I shoot 60 grains of 3f, which would be the ballistic equivalent of your load, and has been accurate in every rifle I own. I stay away from conicals for the most part, and when I do use them, they are on the light side. The Hornady PA .50 Conical is a good performer in my rifles. Really, 60 grains of powder, and a PRB is a great load in all my rifles, from .45 thru .58. I prefer Swiss 3f, but Pyro P is good also, giving identical, if not slightly better velocity than Swiss. Goex is a weaker powder. If it is all you have, it will work, but you might need to use more to get similar results. Whatever you do, don't try and "Magnumize" your rifle. Moderate loads are sufficient, and typically much more accurate. I would sight in about 2" high at 50 yards, that will put you pretty much on at 75, and a few inches low at 100. That will cover 99% of your shots, and the remaining 1% you shouldn't take anyways.