Remington Model 7 and Model 700 barrels are interchangeable. You can put a 700 barrel on it if find one of those for cheap. I would offer you my old .338 WinMag barrel, but the only thing it would be useable for in a Model 7 would be to open your bolt face, and cut about an inch off the back side and making it a .338 WSM.
You would have better luck just buying a cheap .243, .260 Rem, 7mm-08, or .308 barrel for it.