"It looks like the first L A Times-Mirror GP Oct 11-12, 1958,at Riverside. 

Car #110:   Both Bobby Unser and Ak Miller had track time that weekend in the Mille Miglia Kurtis.  Ak replaced the Chrysler Hemi with a Oldsmobile motor for this race. It sort of looks like Bobby's helmet. MotoRacing indicates that Ak drove in the race but a film of the race mentions that Ak gave the ride to Bobby while Ak started in his sick Devin-Chevrolet Special. In any event, neither finished the race.

Car #93:  Listed as Floyd Burt of Inglewood, Ca.  Burt was a Triple 'R' road racer and claimed to have some circle track experience. The car is listed simply as a "Buick Special". I remember 
seeing the car but I never read anything about it.

#140:  USAC Indianapolis driver Bill Cheesbourg drove Alex Budurin's Kurtis-Buick.  He started but was a DNF in the race. Both Cheesbourg and Budurin were from Tucson, AZ.