Don't worry about that inner clutch housing, it can be replaced and the new one is a much better design.
Great news on the Model, Type and Code, I can now tell you it is a real early one for a Scotty as the Scotty 45 was first introduced in 1968. Your engine was manufactured on the 21st July 1968! Wow! Good luck with the overhaul,
Please do not PM me asking for support. Please post your questions in the appropriate forums, as the replies it may receive may help all members, not just the individual member. Kindest Regards, Darryl