If there where a tool. It could be done. You would have to dis-assemble the cooling head. The tool could be attatched to the button head then you would have to zero the device by pushing the button head against something flat. This would give you a zero reference point. Now re-assemble the button head with the device still attatched. At this point you can bring the piston to TDC and the gauge should display a clearance difference between zero and TDC.

Pass you soon...