Which box is that? The solid coated one? In which case that effort deserves an accolade. Blind layshaft bush and layshaft are prone to wear, it's choose a better layshaft or have existing shaft cleaned up and custom undersize bush made. Dunno if you have been lucky here. Plenty on the Forum to guide re assembly.
Sleeve gear bushes also wear, but this is not so critical, new ones too tight on the shaft and they will seize. Sleeve gear lubrication is poor, but drips from the mainshaft mean some oil is getting there.
Throw away that worn sprocket, get a new one with an extra tooth or two for a more relaxed ride and a slightly inaccurate speedo. Heat up the castings, bushes and bearings in the freezer. Clear out the blind holes, look for bent through studs. All threads into alloy are Whitworth, except for the clutch lever ball adjuster cover.
Swarfy.