I'd say the deck height of both is 212mm.
The crown heights according to the Mahle catalogue is:
M42 = 31.65mm
M44 = 30.4mm
Difference is 1.25mm which happens to be 1/2 the stroke difference.
Putting it another way:
212mm - 140mm - (81mm/2) - 31.65mm = -0.15mm (i.e. piston top above deck)
212mm - 140mm - (83.5mm/2) - 30.4mm = -0.15mm (i.e. piston top above deck)