MG Car Repair: 1973 Midget engine number, moss motors, vin number

Question
I have a 73 midget that I am rebuilding.  It is supposedly a one owner, one
mechanic car, being my wife's late father's car.  There are some parts that
don't mesh with any parts books, so I am curious.  The engine ID is
12V/9712/L9975.  The heater box appears to be a 1975 design, and this all
makes me wonder if there is more of a history to this car than I was told
before I started on it.  
Any info will be appreciated.  

Answer
Hi Greg,
I don't have the starting and ending engine numbers but the prefix of 12v indicates it is a 1275cc Austin engine which were in the Midget up to 74, and the 75 Midget didn't have an Austin engine, it had a 1500cc Triumph Spitfire engine.
Moss Motors are a good source for data like that so you should call them with your engine and Vin number and see what they say. There is an MG registry that also has details of numbers.
Moss - 805-681-3411