like 2M sez, Honda used gear cam drives in the high perf versions of the 750 V4's That might be a hint, after a chain it's hard to beat gears for skinny.
View attachment 158919
These are the intermediate gears cam and crank gear not pictured. Note loaded split gear to reduce whine, an integral feature of straight cut gear sets.
But you could swap out a cam chain 10 times from running to running quicker than you could build one custom cam drive. With the factory racing stud mod you could change the chain without removing the motor or even the carbs, getting it down to a one hour job with practice? IMHO the chain is easily good for 20-30K miles. Seems like there was a Euro guy that really racked up miles and he did top jobs at about 60K intervals.
If you want to get fancy methinks the factory design could readily be modified to accommodate an adjustable front guide allowing for easy
external cam, crank indexing. Those two threaded front guide mounting inserts changed to longer threaded pieces with locknuts instead of fixed heads, done.