you will find that some seals etc will also need changing, got 2 friends who have had boxes rebuilt by motorsport compnay over last several months to have clutch diffs fitted (1 friend new some synchros were worn), turns out that once opened even more synchros were worn even you couldnt really feel it drivin car so whole lot were changed along with some seals and other little bits, new mf gearset was also fitted
other friend just had clutch diff fitted but turned out more synchros were worn than expected (he runs boosted 1.8 though) and again made sense to change little seals etc at same time
they used oem synchros and seals etc but ordered them from some company that gets them directly frpom honda japan, was way cheaper than honda here but still dear overall so defo give baz ctr above a shout