Hi Mark,
I use Castrol MTX in the gearbox and clutch - or any of the medium weight modern gearbox oils, such as Silkolene or Belray.
Plugs are B8ES with 20 thou gap. What carby are you using? I have specs for a Mikuni on later model 370 that should be pretty close. Let me know if you need any more info.
Cheers,
Mark