I'm sure you COULD convert 219s with wrecked barrels to a higher intensity ctg. than .22 Hornet or .30-30. Whether you should or not depends on a number of things.
If the new ctg. has more recoil than the originals, you would at least HAVE to glass bed the head of the stock to prevent cracking (or MORE cracking in many cases of older guns). Then you would have to consider whether the recoil would be manageable by YOU.
The only such conversion I've ever fired was a .30-30 that had been rechambered to .30-40 Krag because the chamber was deeply gouged in an attempt to remove a stuck .30-30 case. Recoil from a standing position was certainly bearable. I would not have enjoyed sighting the gun in from a bench, but how many times do you do that with a hunting rifle (the guy that owned it had fired a total of 4 rounds to get the new ctg. to zero, and he used it only for elk hunting). I once had a .35-30AI wildcat on a relined 220 shotgun barrel, but that is hardly "high intensity." Nice shooter, tho.
With me, and many hunters, adrenaline cancels out the recoil when actually shooting at a live target, so if the gun is strictly for hunting big game, the recoil isn't really a factor.
The rimmed case needed for 219s is also a limiting factor. I'm sure some bright gunsmith could make a 219 extract a rimless case. But at what cost in time and loot?
I could see converting a .30-30 219 to a few rimmed ctgs with more horsepower, the .375 Win, .444, and .356 Win come to mind. But how much advantage do any of these have over a .30-30 with modern powders and bullets for lower 48 big game? And for AK hunting critters that bite, would you really use a 219, however powerful?
I realize that "rifle loonies" as John Barseness calls us, will do anything for fun, and I do endorse fun. Just do your " higher intensity" experiments on wrecked barrels only, and I'm interested, for sure. And wear safety glasses. 9.3x74R? GO for it!