You likely know more than me about these bikes, but there were several iterations of Rockets made from at least 1961. Super, Gold Star, Lightning, etc.
A50B & A65D would be a Lightning Rocket.
64/65 era A65's are quite a bit different than later A65's. There is even a fair amount of changes between the 2 years. Here’s a decent guide: BSA Models 1961-74