Studdy those photos very closely. Why is there so much rust on the engine? It isn't a gasser, those are glow plug dirvers foran onboard glow system. They are rusted also from the looks. Also did you notice it is two glow plugs per head?

You might download the manual and spend a bit of time seeing if parts are avaiable for it. Pay attention to rocker arm brackets, all of the carb parts, and exhaust pipes. Twins with the bottom exhaust like it tend to crunch the exhaust pipe on a nose over. Most of the parts are probably common with the 65 single, but one or both cylinders isn't going to be unless Saito made a two glow plug head single. The intake manifolds are different also.

You might PM W8YE and get his opinion on the engine before commiting to it.