Ugh, That is a tough call. I would opt for just repairing the mechanical issues (tube) and staying with the original anno.
Why: History and intended use. Did you buy this duck as a Loo duck? In other words, did the history of this marker attract you to it, vs others for sale? If so, it might be advisable to keep it as true as possible. And I agree with idkfa, if you are going to love the hell out of it, why reanno now?
Another thought: I have not used the shop that you are intending to send it to for reanno, but I would also be worried about loosing the 'Kamikaze Shooter DD-68' label during the anno stripping process. Too many times anno jobs have sent markers out of tolerance, not just removed shallow engraving.