Can I offer one piece of advice? Square Fours are often difficult to get right and at least 1000 miles and / or a years's riding can be expected before the bike is right. But once you get a Square Four right it is unbeatable for reliability, in my experience - which includes a trip to Romania and back (via Poland).
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.