I have already mounted the A/C unit inside (used weld studs) so the firewall cover was welded over the top. I did trim the lip around the original A/C section of the firewall so the cover plate laid flat over the top. I actually changed to a different firewall cover that has some bead rolling in it, fit well and looks even better IMO. I don't have any pics but it's this one.
https://modshopinc.net/store/index.p...7krp6jchtjqui1