I have done a bit of digging, and come up with the transmission details for Ray's single Triumph.
In 1975 he tried running the bike as a single speed, but was not able to run quick enough.
For 1976, a rather novel transmission was prepared.
It was a Laycock overdrive unit fitted into a custom made ally casing. The shift was actuated mechanically.
Some racers were really inventive in trying to solve the transmission issues, which were a major problem for bike racers - as the trusty AMC box and clutch was no longer man enough for the job.
Pete Davies did much of the engineering on the revised bike, which was upped to 875cc by use of special Morgo barrels cast to Ray's requirements. It may have been a Triumph motor, but the crank was a Derek Chinn modified Norton unit.