I had a customer bring over his 68 Z/28.

It was already painted and buffed by another shop and he brought it to me to fix all the problems, lol.

One of the issues was the top of one of the fenders not mating up to the windshield molding, just horrible fitment with a large gap.

At the factory The door hinges were located on the end of the door using a fixture which indexed the hinge to the outside profile of the door skin in order to align with the Quarter panel profile properly.
IF you tilt it out at the top- the profile will be fat in relation to the quarter panel.
If you move the leading edge out from the body in it's entirety will the door and rocker still be in alignment, can you get your seal good enough PLUS will you create too much gap at your wiper cowl to fender gap?