This piece is extremely popular and during Tempus last 2 weeks, the only available 5 pieces were snapped during the first day!
I happened to meet a couple who were so happy to find it in Singapore (as in Switzerland, the queue is up to end of this year)... and do take a look, you can just feel their exhilaration :
chopard.watchprosite.com
As the GT XL Chrono's layout looks like a 7750 and comes with the beautiful solid caseback (which is back-stamped with the Millie Miglia route), I believe that's the reason you have guessed the movement is a 7750.
However the movement used is Valgrange A07.211.
Kong