Spent a bit more time today stripping it down. There seems to be oil and water mixture sitting on top of the rockers so more than likely has headgasket issues.
I also noticed that one of the thermostat bolts was missing and after looking further, there is no thread for it either. Looks like it might be easier to source a good ssecond hand head when I remove mine.

Also spent a bit of time just cleaning bits up. Arches came up really well and I also spent 15 mins polishing the intercooler. Came up pretty well.
Pics to follow