Hello Mate
Easiest way is to turn it upside down (make sure the plugs are still in) and measure how much water/thin oil one combustion chamber holds/it should be 57cc in volume. Any less than that and you know you've been skimmed. If it has and you're worried about raising that compression ratio, I sell Felpro (not something dirty Bert from under the arches produces in his lock up) 'head savers' which are made of solid copper and are
are 0.040 thou (1mm) thick which you fit between the block and head gasket
to restore original C/R.
Hope this helps and if you've a need give me a yell.
Luv N Huggs
The DR