Drilled out the knackered bolt after trying impact screwdriver and hammering in a torx bit.. neither worked, so it was in with the drill and screw extractors - which was kinda nervewracking. Anyhow, bolt came out just fine, so spent couple of hours on saturday and sunday soldering, fitting up, swearing, cutting, resoldering, fitting up, swearing again, fitting up, cut my finger, ... (I think you can see how this went!)
Anyhow, I now have a brand new generator sat inside my engine. Engine cover is back on, everything is refitted and torqued up. Just waiting on a replacement for the bolt that was drilled out to turn up, then I'll fill up with fresh oil and coolant and get it all tested.
After that, its time to do the chain and sprockets and get it MOT'd.
One day, I might even get to ride it!