Dial, case and movement look all original to me. The dial is a little tired, and the design is a little different from the ones usually found on these cases but I think it's alright - it doesn't look like a repaint. Price is starting to be plausible.
A similar case are those Zeniths made in the mid 80's using remaining stock from Martel movements.
@LouS has a very good post on one of this examples here: https://omegaforums.net/threads/zenith-tri-compax.5711/
There is one for auction at Auctionata currently:
![]()
Link to auction here:
https://auctionata.com/o/121638/zenith-full-calendar-chronograph-switzerland-around-1970
Taking into considerarion the skyrocketing prices of the UG Tri Compax from the 60s, perhaps this is a good oportunity to get a more modern one with a reasonable estimation (2400 EUR).