I think it would work pretty well, provided there's enough 'meat' in the barrel to increase the bore size. Usually with Savage 99s in .308, they have a decent sized barrel, so you should be able to go up to at least a .338 Federal without too much trouble. The nicest part about reboring rather than rebarrelling is that there's no other finishing work to be done; the barrel is already blued and the stock doesn't have to be altered. I've been looking at reboring an old .250 savage barrel for a 99 that's been shot completely out (no rifling left at ALL). I'm thinking a 6.5mm x 250 or a .270 x 250, depending on how much they have to work with. Get the old girl running again.