Hi Michael, i can what your thinking, new wrap maybe?, not too expensive?, its your call. Certainly would make it a bit more pretty, allthough i think leaving it as is, is best. Allthough not likely an original koshirae, i think what you have as a feeling of authenticity. Taking that away, i think may be detrimental and may put off future buyers who may be a little intrigued by the koshirae, new wraps are 10 to a dozen and of no interest, hope you see my point. In my opinion, dont change old.
If you want to do some assembling, find a bare blade, usually cheaper and you will learn a lot from it.
Alex.