Greater head was flat..........I would guess the difference is in the spacers supplied (between the bracket and head) I don't remember what the greater head looks like but there's a chance you don't need the spacers at all (if the head is entirely flat, like the Riva head) or you need to custom make some spacers (if the head is countersunk at the head bolts).
I would guess the difference is in the spacers supplied (between the bracket and head) I don't remember what the greater head looks like but there's a chance you don't need the spacers at all (if the head is entirely flat, like the Riva head) or you need to custom make some spacers (if the head is countersunk at the head bolts).