Hi Ben,
All the bolts were simply zinc plated with a bright dip finish. (silver and not that goldy type passivated finish)
As far as paint colours are concerned there are no records of paint formulas left as Rover destroyed all that sort of stuff when they acquired Scott Bonnar back in 1980. You'll have to get it colour matched from the inside of the chain case which is always the least sun affected part of the machine.
Cheers,
BB.