There are 3 'rear' ends to Z3 with differing width rear wings which in turn affect shape of the side sill where it goes to meet the rear wing.
4 cyl prefacelift - narrowest
6cyl prefacelift Z3 and all coupes - widest
All facelift a little less wide than the coupe/prefacelift 6 cyl Z3 by a few mm I believe- someone on here posted the exact measurement but its was not much, I think 40mm total?
The mounting points all appear to be same but I think the difference will just be how well the rear of the sill lines up to the bottom of the rear wings.
I could be wrongs so the best way to be sure if any share the same sills would be to check realoem for the part numbers.
I'd message them and tell them you have a facelift, there's a comparatively enormous market for facelifts needing sills to coupes so you'd think they would like to makes those sales.