We get negative deck deight in India.
What is the deck height on your modells ?
There is commonly a negative deck height on the piston in a closed chamber, because part of the chamber is flush with the top of the barrel liner.
If the piston came all the way to the top, it could hit the head.
There should be a minimum of .040"(about 1mm) clearance there. No less.
This can be made up of the head gasket thickness, if the compressed thickness of the gasket if at least .040"
If the compressed thickness of the gasket is less than .040", then you need to have some negative deck height on the piston, to ensure that it's at least .040" below the head, at TDC.
The .040" is a minimum, but you may have up to .060" clearance there for extra safety margin. No more than .060", or the squish won't work right.