So how far off center a firing pin strike is acceptable to me?
As long as it sets off the primer, you are good to go. The barrel and chamber have more to do with accuracy than the primer strike.
None of you shoot bullseye in 22 LR do you?? Talk about off center strikes. How about the wind down range, how about the bullet shape, how about the amount of powder in the case, how about setting the bullet straight in the case, how about making sure the mouth of the case is trimmed properly.
NO, you have to be worried about something crazy as a .02 inch difference as to where the firing pin strikes the primmer.
By the way you Savage is more accurate than your Remington, not because of the primmer strikes, but because of the way the barrel and chamber were made.