Jim Hunter and John Rice racing at Perris in 1966. Jim wiped out on his Gold Star and John won this one. T-Shirts were the norm for a long time. One quarter of the field wore T-Shirts in the 80's, the fast old guys. They were practical as it's usually hovering around 95F for what seems to be most of the year.
The Top Guys put on a school to show how to ride the track like it should be ridden. I rode the Lightweights M/C Dist.37 events including Perris TT through the early 80s and it was a fantastic track with flowing fast corners and up and down elevation changes.