Yes, the 94 series ... if it has the same latch lever style... you could fit the other gauges of barrels on. Be sure to get the matching fore end wood and latch assembly for each of gauge barrel. The side lever latch... with latch lever on the side of frame...may be dimensionally different to your top latch model.
You might want to gently polish or hone and polish the bore. That will get the crud out and remove any internal surface rust. Be gentle with that hone and polish.... you are not trying to remove enough material to make a 16 gauge or 12 gauge out of it.
Young man , you don't have any idea what i do in my town with a gun like yours, im gonna make it easier, 30 + deers in on year at Yucatan península at rain forest.