Good luck. Barrels for those Winchesters are usually priced about $10 less than a whole gun. When I wanted a slug barrel for my 1300 (same gun), I ended up buying a whole second gun.
The plus side is, if you buy a second gun, you now have a parts source for all the bits that are going to break, if you actually use the gun. I love my 1300, my favourite gun I've ever owned - killed ducks, partridge, bear, deer and more with it. However, the action bars are junk on them. I went through two sets in 12 months.
They handle like a dream, though, and the stock 28" barrel on mine shoots slugs more accurately than some rifles I've owned.