No reason why you can't get a custom smith the USA who is making a whole heap of custom barrels for the R93 and R8.

With regards to the 45/70, on the sweetest handling doubles I've held was a fausti sxs in 45/70. In fact there is a cheapy on usedguns at the moment.

But I consider the 45/70 the rainbow warrior. Better to get a R93 416 Remington and blast away out to 300m.