Bleed the brakes and filled the diff back up with oil. Put the rest of the interior back together, after reassembling the headlight switch I turned them on to see if it was fixed, walked around to the front of the car to have a look at the lights then walked round to the window again to see smoke slowing coming out of the steering wheel area, turns out whatever I used to try and clean the contacts with didn't evaporate and left a residue on the contacts themselves haha. Oh well, the left hand light still wasn't working properly so I pulled the switch apart again.
The furthest away contact is the one for the left hand low beam, it looks like it wasn't quite making contact properly as when the light was dim if I touched it very gently the light would go full brightness. I tried to bend it very slightly but it wasn't really working so I took my spare HR30 stalk apart and swapped the white part that the plug goes into with the two screws in it, this seems to have fixed it. I cleaned everything off as well so no more smoke

this is a full current through the switch setup like the other early Nissans/Datsuns by the looks of it.
Had a go at tightening up the steering box as well, different people have different methods but I went with the one that made the most sense to me where you adjust it with the steering at full lock as this is the least used part of the gear, if you adjust it up on the centre (most worn) part of the gear when you get to the least worn part it's going to be over tight. Somebody had tightened up the power steering line so that it was blocking access to the adjuster screw so I had to undo that and move it out of the way. I haven't driven the car yet, I'll have to see what it's like tomorrow.