I get it... basically fitting multiple barrels to a single action (or actions to barrels, because of stored dimensions). Are you using the integral magazine and floorplate, or do you have detachable mags? Asking because it seems that you must standardize on the same case, e.g., .243, 7-08, .308 if you're using the integral magazine and feed rails... correct?
I'm a huge M70 fan. No reason an M70 couldn't be fitted with a 'Wimage' barrel nut... you could index off of the extractor cut, know how many turns to insert the barrel down, and then just tighten the nut. Combine it with an M70-specific DBM that supports AICS mags and you'd have something.
I wonder why not even one gunsmithing operation in the US doesn't do this... is it that M70s are just not at all popular any more? Or, orders flat/unletted stock blanks and has their own CNC inletting for M70s... pre-64, the '80s-'00 New Haven Classics, and the FN Classics?