Rebarrelling a Winchester 94 is not hard to do at all, but you need the right tools. That barrel swap from .30-30 to 7mm Waters should require no other changes.
At the minimum, you need vise blocks to fit the barrel over the chamber area next to the receiver. You can make these from aluminum blocks on the lathe, or from hardwood blocks by drilling out with a drill press. They have to fit TIGHT or it won't work. A large bench vise is needed, as well as a receiver wrench with sheet aluminum padded jaws. A large crescent wrench will work too. The small barrel shank means that the barrel will not be nearly as tight as on say, a bolt action rifle.
Disassemble the rifle, and remove the magazine tube. Apply rosin or talcum powder to improve grip. Clamp up the barrel in the vise as tight as you can get it. Grab the receiver (with proper aluminum padding) and unscrew it from the receiver.
Installation is the reverse, and if you are lucky, the barrel will index properly (sights aligned vertically, extractor slot aligned). If not lucky, you will need a lathe and chamber reamer to fit that barrel to the receiver.
HTH
John
