The majority of original "board track racers" had no brakes, no clutch, no suspension and no throttle (only a kill switch to slow down) they were push start (without compression release); they were direct drive with high gear only. They were built with one purpose; to run all out on a board track.
I suppose a person building a replica could add anything he wanted; probably brakes and throttle would be a good idea. That little skinny seat won't do your backside any favors either and bent over far enough to hold those droop handle bars might get old after a few miles; and then there is insurance, inspection, title and registration which seems to be out of reach in most states as stated above.
Will