If you go to Vintage Karting which is where that video came from and look under Riverside race you will see a battle between twin West Bend 820s and a kart with a Konig alcohol boat motor on it. The Konig swap was built by the West Bend Guru in Calif-- a super nice guy that I got NOS parts from for my Tom Thumb. I am still looking for broken Konig cranks for him as I used to race Konigs on Hydroplanes. That kart is insane and will walk by the twin West Bends.
i think that is a C-Open class kart. I used to run Stock Reed Light in 1971, a McCullough kart with a Mac 91B. It handled horribly and I had no clue about set-up. However, the stock engine was one of those that was just hotter than most. I can't believe I never took any pictures of it, or at the races. There was a really cool road course that is now a Safeway and strip mall.