Hello dingaling

'dingaling' may also mean an 'eccentric' - a compliment in my view.

I'm confident the engine is original [I hope BB agrees].
Here's another 450423 with a HK30:-
https://www.outdoorking-forum.com.au/forum/u..._BONNAR_-_Model_45_Restor.html#Post68140

There has been some discussion on electrolysis for cleaning.
Just type that key word in the blue search bar and you will find it.
I guess you know powder coating is out when it comes time to repaint.

Hope this helps.
-------------------------
Jack