My son is working on a 69 coupe that originally had a standard interior and wants to install a custom interior. The door panels of course are different and I am wondering if the mounting holes are the same for custom as standard. I believe the window regulators are different with the custom interior being longer. My concern is that the mounting holes for the door panel are the same. I have a 70 Formula and the mountings are different for the custom interior versus the standard. Appreciate any advice. Thanks.