Looks like a Surtees TS19. Only saying that because the late Robin Smith (mainly raced Chevron sports cars and bought Chevron when the company folded) had one which he ran in the British F1 championship in 1979 and maybe 1980. He won the Group 6 2Litre class at the 1979 Le Mans 24 hr in a Chevron with an engine he built himself. I was out at his workshop to get the corner weights adjusted on my Hillclimb/Sprint car and he was wearing a mask and using tweezers to fit all the roller bearings into the slide throttle assembly.
(Lead me not into temptation, I can get there myself)
