4198 is a very good powder for the 45-70. I like H322 better for very heavy loads, though. IMR 3031 is also excellent for medium to heavy loads.
As for primers, I use Rem,ington 9 1/2 standard large rifle primers for all of my rifle loads except the belted magnums. (Remington 9 1/2 M for those) I've used nothing but Remington primers in all of my reloading, both rifle and pistol for over 25 years and never had a primer related problem.
If you think a mighty military force is expensive, wait 'til you see what a weak one costs.