A little update: The GMT module works, but not flawlessly, it stutters, especially after I have set the GMT hand. But it runs. I will together with a friend take a look at it. The movement itself runs well now. First it was unreliable but now it ticks strong. Maybe the movement needed some time to tune in. Still it will be serviced.
I thought I should make some overal comments over the design: I think this is a really nice watch. I don't know much about it's history, but I really dig the color palette. You have both red, blue and white in the inlay, orangey lume, goldish text print, red gmt hand, silver hands... It came with a riveted stretch bracelet. If you have hair on your wrist, it will be a PITA. I thought the bracelet was decent, but this watch, with all it's colors, screamed leather strap to me. The I found the crown surpringly small, but I'm used to big crown designs. I actually think it looks more balanced with a small crown, but I still feel for the big crown design. What also appeals to me about the 6542 is the case profile. It's really sleek and low, with pam 6154-ish pointed lugs:
My plans are this: a relume of the dial and hands plus some ageing, dull the case a bit, swap to Clark plexi (already bought one), change the GMT hand - it looks off to me, and a leather strap. I was planning to make new plexi inlay, but this I have put on hold. The time is just not on my side at the moment. The plexi inlay is itself a very cool design feature. The one I have looks really crisp and perfect. Maybe too perfect compared to the gens, that has distorsions, blotched numbers and a creamy discoloration. Some seems to be slightly curved/rounded, some looks flat, like this one.
I have dyed veg tan leather and made a strap just as vintage pam straps were constructed: double folded tail side and three folded buckle side. The buckle was taken from a NATO strap. A slightly meatier buckle would be preferable, but this is what I have in 20mm. I stitched the ends to make the strap more robust. It's a bit orangey now, but will darken with time, use and mink/neatfoots oil.