There's not much concern with an early Hi Wall action when it comes to original chamberings. You can really hotrod an old Hi Wall as they're very strong and have been chambered in all sorts of extremely high pressure calibers.
The famous barrel maker Buhmiller back in the 1950's tried his best to blow up a Hi Wall action, and finally decided the only way he could succeed was to chamber it in .30-06, thread the end of the barrel, and insert a pipe plug before firng. Upon firing the barrel blew off the action, but the action held! He finally gave up trying.
If you pull it apart you'll quite possibly find the caliber marked on the extractor. Many old Walls had it makrked there.