Oddly, the search function came up with nothing...has anybody rebuilt their Gen1 5-speed tranny?

The 2nd and 3rd gear synchros on mine are starting to get a little "notchy", and 5th gear whines more than I think it should (4th is dead silent, to give a comparison.) I'd like to get both of those fixed this next year.

How hard is a transmission rebuild for someone who's mechanically inclined and has a fairly well-equipped home shop? Would it be better to buy an already rebuilt one?

1987 Montero SWB, 2.6L, 5spd
Weber conversion
2-valve head from Engine Machine Service
"4G54 FTW!"