It appears to be a Black Lightning, which was the factory built racer. The pipes and carburetors are correct. The gas tank is interesting, I've never seen one like it. I suspect that it was for a long distance event, maybe the Manx GP that was held in the fall for amateur riders.
2015 BMW R9T, 2010 Ducati 1098 Streetfighter S
2009 Kaw 650 Versys, 1967 Triumph 650 TT Special