Gosh, they are very similar!
I've decided not to be so lazy and to cast another cylinder head, the metal is in the furnace as I type.
I had stupid problems moulding the sand. First attempt, I'd opened the mould and put in a screw to lift the pattern and as I removed the screwdriver from the screw it caught in the Phillips recess and dislodged the pattern. Second attempt, the sand dropped out as I opened the mould! By now I had run out of talcum powder as parting so I used some fine dry sand, that worked fine.