Boldt leads Bucknum through Pomona's Turn 3 on lap 1 of the April 21, 1963 main event.  In 3rd place here is Rod Carveth in his Buick-powered Lotus Mk.19.

I remember being very surprised that the car/driver combination of Boldt and his Kurtis was a match for Bucknum and Old Yeller III, and pretty much everyone else in southern California racing that year.