What a great opportunity to have someone willing to teach you how to use a lathe, however there are few special tools needed for rebuilding a Norton gearbox. The most important one is the tool to remove the slotted lock ring that holds the clutch operating lever body in place. I have found that all of the bushes can be pressed out and the new ones pressed in with a selection of different sized sockets and a vise. The main shaft can be used as a reamer if you clamp it in a vise and push the gear with the new bush onto the splined part of the shaft while turning it by hand and with liberal spray of WD 40 it will be reamed to the exact size required.