Out of curiousity I did some looking around to find out what all was involved in such a conversion.
From what I can gather, it's more than just a barrel change thing. Evidently, you need to have a special bolt and recoil spring assembly too. From the costs of the barrel, bolt, and spring set-up, it looks to me as if one could buy a new carbine in .17 Hornady Mach II for about the same money.
FWIW, I think I'll just look around for a nice, used Ruger 77/22 at the right price to experiment with. All I'll need to get is the new barrel in order to see what all the fooraw is about. 96/22 would be fun, too.