Welcome to the Club Ron.
Your engine went to Kings Motors of Oxford on 23rd June 1938. Oxford is one of the very few places where they recorded engine and frame numbers on the registration records - which still survive. So you could find out the original registration of your engine, plus, possibly, the name of its first owner by contacting Oxfordshire Archives.
36 4G, 37 VH, 54 KH(A), 75 Healey 1000/4, 52/53 ex ISDT KHA (project).
Former Machine Registrar & Archivist, General Secretary and Single Spares Organiser (over a 25 year period).
Now Archivist once more - but not Machine Registrar.