I think what you have there, is a picture of a twin cam, 4 cylinder Offy, I don't recall seeing or hearing of a 2 cylinder, have/had pictures of the 2 cam Offy, very few of those were built. The one in your picture looks like one of those. Woops, shoulda looked first, they did build a couple of "2 cylinder Offy's", by using the front half of a 255cu in engine, the "odd" one I was thinking of, was a "single OHC" 4 cylinder, of which very few were made also. They refered to the 2 cyl, as the "Backdoor Offy". Bob!