In Westfield they could do the pre-1960 threads to replace a barrel or convert a gun.. but the new 99's had a different thread pattern. And the post-900,000 rifles have different internals than the pre-900,000 - so you probably would have significant problems getting a 22HP/303 Sav/30-30 to work in a 900,000+ gun.
Now.. you could find a 1950's 99F in the 7xx,xxx range in 300 Savage and convert it. Parts would swap with older guns much more easily.
I'd just find a beater 99T and put it on.
