I didn't take it apart and can't find a good reference - regarding windlace and the rear quarter panels on a '66 fastback. Does the jam windlace press over the rear quarter's front edge and the jam - or does the edge of the quarter panel rest against the jam's windlace?
I'm having a little trouble understanding the question, by rear quarter panel, are you refering to the interior quarter panel? If so the windlace goes over both the metal jamb and the fiberglass interior panel.
EDIT: I'll go out in the garage in the morning and double check for you.
Here are the best pictures that I could find, right click on them and save them to your computer, then you can enlarge them if it helps.
THe interior panel rests against the windlace. Put the windlace on the door jamb first. Too hard to get the windlace on under the panel after all the screws are tight-have to loosen them back up...