Hi SimRice,
The engines date of manufacture is 19th July 1976 and is definitely of the right era.
I use a product on my chains called HHS Drylube by Wurth. It's a dry synthetic wax with PTFE that is specifically designed for chains and has excellent creep/gap penetration and doesn't attract dirt. Unfortunately it's bloody expensive and normally only sold to trade. You might consider hunting it down if the grease bothers you.
