Besides his supermodified adventures, Billy Yuma was a pioneer of, and the first champion of the Tampa Bay Area Racing Association (TBARA) in 1973.
Billy competed in NASCARS Grand Touring division in 1968 and 69 with some success, see his results
here.
He also competed in the 1968 Daytona 24 Hrs in a Chevrolet Camaro with team-mate William Boye. they finished 16th (3rd in class) completing 540 laps... not bad at all!