I don’t know if this will be of any help but many years ago when the original 410 starter motor gave up I got a geared replacement from the UK Jensen specialists Cropedy Bridge Motors who were just down the road from where we then lived. I bore it home in triumph on the back of my bike! It fitted perfectly and improved things enormously. 
 
As you will know Jensens used the 7 litre Chrysler engine, from the USA 
 
The point of this story is that it suggests that the Chrysler used exactly the same starter motor across a very wide range of engines and you probably don’t need to focus too hard on the exact engine type or where it was originally built 
		
		
		
		
		
		
		
	
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