I can not pinpoint it exactly but late 1960s to very early 1970s would be close based on the cover. Most parts for this engine did not change until Chrysler sold out to Brunswick. Pistons are NO LONGER AVAILABLE anywhere. I know! Several years back I bought the last two in the country.
Sometime in the late 70s, the lower unit was changed.
Points and condensers can still be purchased at Chicago Magneto.
Typically, if not abused, the only thing necessary to do to get these engines running is to remove the flywheel and clean and set the points (.020) Then, remove, disassemble, and clean the carb.
Yours is electric start and the starter is Prestolite. If broken it can be rebuilt OR you can usually find a used one on ebay. The engine can be pull started using a lawn mower pull cord around the top of the flywheel.