I'm not sure if you're thinking Weaver base or not but this might help. Fits a 336 or a 444 or an 1895 and several others too. Thanks Marlin!
click here I've used a steel redfield type base in past and now am using a Talley base and ring. for the 45-70s.
To test accuracy of several rifles with one scope I'd put a Weaver base on all three and swap as the mood strikes.
Good luck!