Quite a rare beast, when I was an apprentice around 1969 we had a customer with the saloon version of that six cylinder engine, from memory it was a well worn example with a thirst for oil.
However if yours has survived all that time it sounds like well worth preserving and quite unique, I have never seen one in the flesh since that time in 1969!
What are the legal and emission requirements where you intend to use it?
Are servicing parts readily available along with people willing to work on older vehicles where you are, as many modern workshops run a mile or charge silly money to work on anything they can't plug into a computer to tell them what to do.