Welcome to The Board. Yes, your boat appears to be the same as Aarons. Perhaps you guys can start a Club? Somewhere in The Board, I posted some pics of yet another one of those boats which I came across in the Southern suburbs of Sydney (no motor) about two years ago. No, it wasn't yours.
Anyway, I have a very good friend who use to race one of those McCullochs on a 12 ft Haines in the mid 1960's. Believe it or not, this friend who I met in 1973 is now 71 years old and still racing boats. He has a collection of over 70 outboards. I'm very confident he can steer you in the right direction when you are in need of parts. Your water pump impeller is the first thing which should be changed, before you launch her.
Let me know if I can assist.