I have one cylinder reading at 85psi when hot,the other three are 100, 110 and 115.It is a 73 two litre.I have the wrong CHT, either a 012 or 003 instead of the 017,MPS ECU etc. are stock.
What symptoms should I look out for if the low compression is affecting performance?

The spark plug may look different. You should adjust the valves and re-torque the head to see if it gets better. Long term think about a rebuild.