Hi OCDirt,
From your pictures, it looks to me like it's had some repair work done to the front rail around the engine mounts. I would have a close look at that to make sure that it's been done right. I agree with Jack and Darryl that the engine doesn't look original. For some reason the air cleaner cover and fuel tank cap look to me to be older than the cowling. If a newer cowling has been swapped onto an older engine, that will make dating the engine much harder. I'm really only guessing though. The main considerations will be the condition of the chains and sprockets, as Darryl has mentioned, and how the rest of the machine runs and presents overall.
Thanks, Michael
