|So after my head was stolen from the machine shop I had an old head sent to me from a friend in the UK who had it at the back of his garage.
We are pretty sure it is off a Sunbeam Lotus S1 911 motor as these are the only Lotus my friends and I had. We went through 6 of them between us.
The casting number is 907E 0311Y which doesn't narrow it down too much but the last digits of the engine number are stamped on it, 19871D which I can see as between 1978 and 1982. I think it is a 1980 but can anyone narrow it down a bit by comparing to a known age serial number.