It's hard to tell exactly what action it has, but if the action is stamped Springfield 1898 it's a Krag, and definitely NOT a strong action. The max pressures on Krags is something in the low to mid 40kpsi area, and if loaded too hot things could get rapidly out of hand. A .219 Imp Zipper in a Krag action would likely be about equal to a .223 Rem in ballistics unless the shooter wanted to wear the bolt through his head.
The Improved Zipper was probably popular back when Zipper ammo was factory loaded, but now would require necking down .30-30 cases and be a pain in the tail when other factory made cases are available, like the .22-250, or simpler wildcats like the .22 BR or .223 Ackley Improved. Factory .219 ammo can be fired in an improved chamber which will blow out the case to fit the improved chamber.
If the rifle belonged to me I'd either keep it as a historical item or sell it to a collector.