What kind of results are you looking for that the .270 or .243 won't give you? Really?
If you just 'want' another round, then by all means, go for it, the .25-06 is a good round. Where it shines, though, is at ranges way beyond 100 yards.
If you want a .257 Roberts, check at Midway for an A&B barrel, and find a decent M98, put the two together, stock it, and enjoy! In just the last few days, an older M77 Ruger showed up in a used gun rack, at $350 asking price, and a friend tells me of one in Michigan, a 722 Remington for about the same money, well within the means of a modest "playtoy" savings account.
In the same range, as far as cash outlay, rebore that .243, or pick up a Hornet barrel and do it.