Pat Riot is right.
I started with 38-55 and finally wound up with the 45-70. The story is too long to tell but suffice it to say the 38-55 is a fun round and won't beat you up but has accuracy problems and will not shoot to 500 yards consistently. Go with the 45-70 and save the grief.
THERE IS A REASON THAT THE 45-70 IS THE MOST POPULAR ROUND.
Good luck, Conejo