I've looked into this myself, I have a really nice/well done Type 38 with Lyman rear peep. It used to be quite common to run a .257 Roberts reamer through the chamber, and 6.5-.257 dies are still available. I ended up doing a chamber casting of mine to make sure, its still a standard ("sloppy") 6.5x50 Japanese.

I never could figure out if a .260 reamer would adequately clean up the chamber, but I also thought about maybe even a 6.5x57. Unless you simply have extra .260 brass laying around, or want to go through the trouble of forming your own, 6.5x50 brass really isn't any more expensive right now than .260 (I just ordered a couple bags from Grafs). Bore issues would be a concern more than the chamber, though. I actually have another .260 rifle, and have a decent amount of .260 brass...otherwise, its easier to just by the correct brass and be easy with the resizing die.

I would be very interested in your stock, if you decided to get rid of anything on the rifle. I have a few Type 38's, one with a cut down/sporterized stock (everything else is mostly original, with mum intact). I'd love to be able to put it back into an original stock! As far as one with a ground mum, I wouldn't hesitate unless it was some rare model/type/arsenal.

This is one of the nicer sporterized ones I've seen...

[Linked Image from i.imgur.com]
[Linked Image from i.imgur.com]
[Linked Image from i.imgur.com]
[Linked Image from i.imgur.com]