That may be a story, FPMXer, it would not need an extra rev limiter. There is a rev limiter in the ignition, but only to prevent an engine failure. You wouldn't want any restrictions hillclimbing. If it was used for competition hillclimbing, it would be equipped with a deadman switch that has a tether that hooks to your hand or roost protector then kills the ignition, if you bail.
I would guess a 93 by the forks, but a very nice find none the less...