Spitfire 4/Mk2 cylinderhead gasket thickness

[claus@triumphracing.net]

I'm trying to calculate the compression ratio on my Spitfire 4 with the
Stage 2 cylinder head. I have the chamber volume and deck clearance as
well as the given dimensions from the bore and stroke, but can't find a
measure of the head gasket thickness when compressed. I use a standard
4/Mk2 head gasket and standard torque settings. Does anyone have a figure
for this?

Regards,
Claus Ebberfeld