Early Disc Brake ?

warwagons said
It has got a single Master cylinder on it which looks odd. Looks like a regular drum M/C but about a 1/2" taller. How do you differenciate the two?

The taller m/c is the correct one for the KH discs. It's actually a bolt-on extension so the m/c has more fluid capacity for the calipers. My car had one too. It's also a KH disc car. I recommend replacing it with a dual m/c, though for safety.