No, I haven't, but thought about it for load work. I can't see putting any big scope on a .45-70 for hunting, it's just not needed for the ranges encountered in any big game hunting, specially with the .45-70 which has MPBR of roughly 250yds give or take, it's not a flat shooter and taking game at ranges beyond the MPBR would be irresponsible with a .45-70. A fixed 4x, 2-7x or 3-9x at most, is all that's necessary. In over 45 years of big game hunting, I've never used or needed anything with more magnification for hunting deer or elk, and 99% of the time, my scopes have been on the lowest setting when game was taken, very seldom do they ever get set on the highest setting, it's just not needed. Varmint and predator hunting would be different, but the .45-70 is neither, unless for fun as knight0334 does with chucks.
As far as bedding the end of the scope rail, some have done it, but I don't feel it's necessary, I've only got 2 or maybe 3 scopes that are big enough that I need to use the Ultra rail forward cross slot, I much prefer the shorter standard rail.
Tim
http://www.varminthunters.com/tech/nef.html