Today my new Vintage Air Gen IV A/C unit arrived and I got it fitted. I'm sure glad I ditched the cable unit because this one works out so much better in my application. The downside is I have to weld mounting studs onto my finished firewall, and make up all new interior hoses. But it clears the radio and the 4 vent outlet will make it a lot easier to duct air to the valence vents.
I also got the mounting holes for the valence drilled through the bottom of the dash (what a pain!) and now I need to install some kind of nuts above the dash lip so they're not loose and to make it easier to install. Don't know if I'll use PEMs or some other nuts I have.