I suppose that a Savage/Winchester style extractor could be installed in the guide lug, engaging the case rim in a recessed boltface.
I know little about CNC machining or the writing of the program, but it should be do-able.
The question is now many units could be sold? Enough to justify the effort?
A single shot conversion can use the original bolthead, with a suitable extractor.
I have a Dugan one piece conversion No. 7 with S&L .308 barrel, Canjar trigger in an early Robertson synthetic stock. While it is a decent enough shooter, I don't use it. It would be an excellent rifle to convert to .223/5.56. No provision for a magazine.
Maybe I'll keep my eyes open for a good take-off barrel with at least a 1:9 twist.
As mentioned previously, a M700 barrel can be rethreaded for a Lee Enfield. So can a Savage (originally 1 1/16-20), if a locknut is used. A locknut can be turned on the lathe, or the receiver ring from a scrapper can be turned round.