ADDITIONAL NOTE: There is  a known issue with rebuilt Fixed Head Coupes, where the rear end or Tonneau panel has been replaced:

The Roof panel is a sprung pressing and needs to be set up with a screen  temporarily in place to set the pre-load in the panel  around the window surround , before welding it onto a new tonneau, as the panel was originally in tension when assembled together. Failure to do this may result in the roof panel having to be reset later on when you are fitting the window AFTER PAINTING. This is the point where offering up the widow to the panel (less seal) will show the problem and the rear window seal and chrome will never fit correctly to the wrong shape roof.