Hi Simon, I owned a 2 pipe square 4 back in 1966 , had a blown headgasket and I paid £15 for it. managed to do the gasket but on the way found out why the PO had wanted shut fast ,he'd broken of 2 of those strange shaped head bolts . it was my first attempt at drilling down a bolt and using an easyout to get the bolts out which I did and got the new bolts and gaskets from Bob Sargents in Liverpool off the shelf! Being a ignorant young twit I got shut soon after fo ranother A10, cheers Bob