There is a company called acdelete.com They make very nice a c delete covers for the firewall I used one in my car and it fits and looks great Good Luck
Update! got the panels re-sealed and the firewall painted, trying to find a heater core that fits, will pick up a ac delete cover when I'm in Denver in a couple weeks. pulled off all the suspension and steering linkage to better clean and paint the frame rails, I'm replacing all the control arm bushings and sway bar bushings with energy suspension parts and ALL steering linkage parts with Moog. as you can see by pics I have headers, dist., water pump ( from ta), 2 1/2" dual exh., gauges, torque conv., and my turbo 400 back from rebuild. painted the frame rails today but haven't taken pics yet, gonna wait till I have suspension and steering back on and painted first. busy, busy
This is one cool build!! I'd love to hunker down in a garage and tear my '77 apart like this, nice work!!