Hi Blomman,
this was a very special day for me as I finally found a vintage Omega chronograph that I am hunting for a while. It strongly ressembles your GP specimen.
This cal. 321 chronograph is in excellent condition and just that type of watch which I value for its clarity and timelessness. In contrast to most Omega chronographs from that era it lacks the tachymeter scale at the dial periphery which renders it more legible and makes the dial look more sober in my eyes.

