There should be spacers int the gaps of the top yoke where the pinch bolts go, basically washers with a flat ground on them. They are there to, in theory, stop you overtightening the bolt and breaking the yoke. part number 53235-300-000 which means they are originaly a 750 part.
The steering lock was originaly same key as ignition and seat and last time i looked you could still get a lock set of all three new but it was a bit pricey plus there apear to be some other bits missing!
I have all the workshop manuals along with parts book and PDI and build sheets for the 500 on a CD/DVD(I think it got too big for a CD!) you can have a copy for the cost of postage plus a beer