Slowly picking away at it. Finally got up the nerve to cut a hole in the firewall. After locating where I wanted it I drilled just the 1/4" center hole first. Then I attached the hole saw and ran the bit backwards to cut through the paint/filler. Then slowly cut the 2" hole. It didn't go as bad as I feared it could.
I mounted the Holley HP ECU under the dash up where the original center speaker should go. I need to beef up the mounting a little bit and clean up the under dash wiring but think this location should work.
