This is what I have found out if it's old news I am sorry
Coupe doors with steel hinges will not fit with Aluminum hinges they are too wide across the pressing inside and there is no way to adjust the lock plate it is too tight! the outside dimension of the door is the same! there is 6-8mm difference between the two types of hinges when put in the parallel position the part book I have only shows one part number! for Mk3 coupe onward.
If the other way around you will need lots of packers! I asked a well known restorer if they had problems and they said they whacked the hinges in the A post and door to make them fit they went aware there was a hinge difference
Here is the difference on the front hinges near enough 6mm Steel ones on the right Now why dont those doors fit
Which ever way you tackle the door gap problem Phil it is obvious at some time things changed as we know in pressings but the hinge problem is one to be wary of particularly if the door has been changed and things have been altered with a hammer my 69 coupe are all ali I have a 71 here at the moment and it has both and I know 110% the hinges shouldn't be that way hence poor door gaps and closing problems
I have alloy door hinges on a coupe that were worn allowing the door to drop when it was opened, but they are repairable. By fabricating a new pin and reaming out the holes and thrust washers , all becomes well again.