hi there i have been given a landrover s1 engine head and other bits, how can i tell,if its a 1.6 or 2.0 head ?

You know, I think they are all the same. The early engines 1.6 and 2 ltr had siamese bores, No1 and No2 cylinders were very close together and so wer No's 3 & 4. Latter 2 ltr's the bores were spread apart but looking at gaskets there was less material at the front and rear of the gasket so I don't think the block was longer for the latter 2 ltr and also there was more material at the front and rear of the 1.6 gasket so again I suspect they were all the same length and as you know the head face is flat with the combustion chamber in the piston and block.
I never had an issue with a s1 head that didn't fit on a block when I was building them many moons ago.