Ah great, I measuered the old gaskets at 1.6mm aswell so that confirms it. When the heads were done the bloke said that should get away with the standard thickness because they only shave 0.1mm and he said they have about 0.5mm before needing to adjust?
Does this sound right or would I be best to try and source a 1.7mm gasket if possible?

Might be a silly question but worth asking before spending any money...