Hi Neil,
Gearbox is close ratio Norton. Frame Yamaha. Engine at 560cc. Bought roughly as per pic a while back when looking for more power in a non-modern package. Carried out a few mods since then - eg lengthened swingarm to keep front end down and made different front downtubes. Changed gearbox to normal ratio as found it a handful for hill-climbs and so switched to sprints, where a CR gearbox is a disadvantage.