If you can actually find a RUM Savage action. You'll have a tough time using it as a repeater. Even with a RUM box, you'll be limited to a short mag box.
Making a Savage into a repeater isn't a big deal. Just takes some time with a dremel or mill. You'll also have to modify the mag box and secure it into the stock.
If you don't mind single shot, that's the easiest way to go. No modifications necessary.
If you really want a repeater and don't want to whittle on an action. It's easiest to build on a....gulp....Remington.
Throw a Wyatt extended box in and go.