Odd little piece is right. I wonder why he is selling it?
The Arisaka action is pretty strong but I don't know what the pressure limits were for the original 6.5 x 50mm round, but probably somewhere in the 42-45K cup range. I'll bet the pressure ranges on the 260 run a lot higher and it might be a bit too much for that action. You may want to check Steve's Pages to see if he has any pressure data on the 6.5 Japanse round and compare that to the 260......
However, doesn't mean you can't load down a 260 to 6.5x50 ranges - either loading in neat short rifle like that would make a great woods gun.
I wouldn't insult the owner, not a bit, but I would try and find out more about the, ummmm, 'success' of the rebarrel. It's a sporterized mil-surp that has lost any collector value. If it's an individual thing to your liking then go for it. The barrel and gunsmithing to put it together should have run a couple of hundred; trigger, stock and bedding probably near the same, so he might have some $ into it, plus the action (see if he has the original barrel). See what he has to say and go from there; maybe around $2-300, maybe half that. I've seen English factory sport-overs of SMLEs which went for $150 on the 'used' rack which meant the store bought it for less. HTH. Mikey.