So everything is now complete.
I have overhauled the diff, replaced the brake disk and square, replaced the pinion gear, changed all the c-clips, removed all the rusty bearings and replaced with nice shiny smooth fresh ones, installed a kill switch, cleaned the carb and added a choke, binned the old air filter (actually had no filter in it at all, just a plastic hood), fitted my old X2 air filter, put new diff and drive cups on along with driveshafts with boots.
The only thing that is left to do is the shell but there's nothing i can do about that at the moment, it will just have to look like a turd for a while. After all that it starts within 3 pulls which was a huge improvement, got a nice idle but will probably need some fettling to get it right at the top end.
All I need is some dry whether on Sunday!