Originally Posted by
frederik
It certainly looks like you've still got the original S engine (which would be terrific). To be sure, you need to find the engine number stamping (right side of the fan, should be something like *61xxxxx*, and run it past someone who can check the chassis/engine number combination, for example member davep. (It might be better to not share the engine number publicly because the combination might be misused by someone in the future.)
By the way, that engine should be thoroughly checked and preferably taken apart before you attempt to start it (as said before). It's puzzling why you don't have the matching tachometer.