Inquiring mind wants to know.

distance from the top of the piston to the bottom of the head surface.

The measurement is basically the deck height (distance from the top of the piston to the top of the block surface) + the head gasket thickness.

Right, what Brian said (except if your piston is above the deck, then subtract that from your head gasket compressed thickness). And here is the long version for your inquiring mind. Click on this link>>>
Quench discussion (http://www.speedomotive.com/Building%20Tips.htm)

For clarification, I would modify Brian's definition slightly to say...

Quench distance is measured from the top of the flat part of the piston (do not measure from any part of the dome,dish or valve reliefs) to the flat part of the head surface (do not measure from any part of the combustion chamber).

Oops