Thats PK751 ...Beecheys old one. The chap that owns Perf. Ignition Systems (Scorcher) has it.
Should have triggered when you said #4...... Neptune Blue....you must have had rose coloured glasses on....lol
There are a couple of replicas of it around as well.
John Reaburn you mentioned .....
John was also a Humpy driver of some renown.
He went onto Open Wheelers and ran with the best of them. He did a lot of racing in Europe
probably culminating with LeMans 24 hour in a GT40.....a real one.