Re-barrel the model 70 in 260 it were me, the model 70 action is the longest of the short actions and could handle the 260 fairly well unless you plan on shooting long 140 gr. bullets exclusively. In that case, you would have to seat bullets deep and may take up a little case capacity with powder and bullets may have to be seated out to the lands and turn the rifle into a 2 shot rifle. That is why I like long actions.
Keep that rifle, it is American made and is a very good, under appreciated rifle action, with a new barrel of a good manufactorer like Douglas would turn it into a tack driver. You will love a 260, the 6.5 cal. performs very well, it just works, gotta love 'em.lightbulb
FE