Hey Rick, not to say about keeping a rifle orginal but a good aftermarket barrel would do better '' more times'' than a orginal one but as many 742's that won't cyc and are single shooters for owners would be the first place I would look consider it a sacifice of one rifle to make your completed rifle and then you would have some extra parts.
Replying mostly to mark but would ask; What is wrong with your current barrel or what is the problem? Have you thought about sending it back to Remington, for repairs ?? ...
First, I would clean it really, really well. I'm talking about Butch's, JB, and Sweets as many times as it takes to get a perfectly clean patch. If that doesn't do it have a gunsmith check the crown. try several different brands of ammo. If it's still bad after that I would sell it unless it has sentimental value. If it does go to gunshows and buy a piece of junk with a good barrel.
The barrel life on those things is not very high, 1-2K rounds at most. They were designed for hunters who go out and tag a deer or two every year for 30 years. If you shoot a lot they will die fast. If you shoot fast and a lot they will die even faster.
"all over the place" does not say much though. I would say you should expect MOA 2-4 and anything worse could be an indicator of a problem.
My 7400 gets 3" groups at 100 will cheap ammo and 1-1.5" with my hand loads. If your muck worse than 3-4" at 100 I'd try differant ammo. If that doesn't help try getting the barrel recrowned.