I would turn the Mauser barrel tenon down to 7/8 inch and thread it to 24tpi vee. I would then install a sleeve which would be loctited in place and threaded to fit the Springfield. The sleeve would have the coned breech built into it and the headspace would be set via the location of the shoulder. It's a bit of work but works out OK. GD
My friend did something similar in adapting a take off M70 .243 barrel to a Mauser he had laying around. It's been a good rifle for him.
