14/16" = 0.875" x 25.4mm (i.e. 1" = 25.4mm and converting inches to fractions first) x 7 (7 white keys an octave measuring C up to B) = 155.575 mm. an octave span.

0.875" x 25.4mm x 7 = 155.575 mm

Are you sure Donny that the Pa800 key has a 14/16 inch width? Can you get a more accurate measurement possibly? If you are correct on the 14/16" then the Pa800 keys are actually smaller in width than my PSR 2000 and/or Tyros key width, which both have a 160mm octave span.. Although, if the measurement is measured as a whole i.e. "from one end to the other" then the gap between the keys has to be taken in to consideration also. So depending on how much gap there is between the keys, and while measuring the distance as a whole (as oppossed to just the key width itself x 7 i.e. C to B) there would be some discrepancy in how the octave span is determined depending on how it is measured.

Best,
Mike