fiberglass dash

I have a 1968 Cadillac Coupe Deville, I have decided that I want to fiberglass the dash so I can custom paint it to match the exterior. I will be doing the doors as well. I have worked with fiberglass a few times and thats not my area of confusion. I want to keep the OG shape of the dash and most of the components. Here are the main changes I want to make. On the top piece I want to fill in the wholes where the original speakers would have gone. There are cracks in the OG vinyl and superficial cracks in the foam. The Middle piece which is currently made out of pot metal, that housed the key ignition, stereo, wipers, and lights, I want to make the piece now hold a new head unit. I am not 100% opposed to keeping this metal but since its pot metal, can't really weld it. So altering it via fiberglass or some other media seems like a good choice. The bottom piece of the dash is where the Glove box and ashtray is held. I want to again keep the same shape and get rid of both of those and make it a solid piece. I understand the concept for making a whole new dash and all that fun stuff, but what about wanting to recreate the exact shape of the original with a few changes. I can add pictures as soon as it stops raining here and I can uncover the car and get some pictures. The windshield is out now so it logically seems like a god time to take on this project.

Come on guys, no one has input?

Im far from a fiberglass expert. My only idea would be to use some mdf and cut out a profile view of the dash. then use mdf where ever the components need to be mounted. once again, i could be wrong, jus tryin to helpUNLABELED Custom Car Club President