A coupe bumper wont fit
if thats what you mean, gt or otherwise cos the rear hatch is different.
There are however gt line/gt 5 door models,tho less common.
A part/parts from that should fit.
Another thing which wont affect body bits fitting but does affect appearance is.
All coupes (3 door) and all gt and gt line models have 12 mm shorter springs than "regular" 5 door hatch and sports tourer models.
Slightly harder ride , but it also means if you for example got 5door gt /gt line rear bits it wouldnt look exactly the same as a gt line 5 door at the rear.
1 cm isnt much,but just in case you did get the parts and compared to a oem gt line in a car park..etc etc.
The good news?.. Ive been in a "regular" 5 door and its definitely comfier than a standard coupe
Have a look at the my mottah section..some 5 door mk3 styling there.