series 1 rover P4 head

Hi All , Im new to the forum but not to landrovers , ive had them for over 40 years . . i currently have a 1952 minerva 80" . I have an ally cylinder head with SU carb from a Rover P4 60 . in my old trialing days this was a common conversion - better carb etc . However i cant remember if it fits the early or late( 54-59) 2 ltr engine as the bore is differrent , Niether can i remember if we used the same head bolts from the landy or the P4 . any one any idea , many thanks
PS anyone know the wherabouts of 1949 80" 607TRR - i owned it for 35 years .