Took the exhaust off, welded up more rust holes that had appeared, cut the muffler back off and extended it by adding in a new piece of pipe with a bend in it, but I still wasn't totally happy with it. So at a later date I took it back off and cut it up again, braised up still more pin holes, deleted the muffler clamp and welded in a straight section of new pipe with a mount bracket welded to it. Welded a matching mounting bracket to the centre stand stopper which I made from a piece cut out of a chrysler rear axle U bolt.
Edit - I tried hard to mimick the original muffler location but have since realised that the original ones have a generous 'dent' for clearance around the axle nut & split pin, so that's why I couldn't quite get it spot on!
Picked up a nice chrome 750 rear mudguard from the wreckers - the only difference between the early 750 and 500/550 items is that the 750 one has a shorter wiring tunnel and a wiring hole near the front whereas the 500/550 one has the wiring tunnel all the way to the front of the chrome piece and the wires pass through a hole in the plastic mudguard piece.
The chrome tail light bracket was one of many ebay purchases that was not cheap!
I've got two projects running simutaniously and seeing as how the 500's tank restoration is finished and it has a new $800 paint job but the bike still has its mystery carb problem I have been using the 500's tank on the ss.