is this garbage necessary?

I am thinking that "valve" started showing up on non ac cars bout 72 maybe??? yes if it works, it is good. would not the difference in ac and non ac firewalls be the location of the holes that mount the boxes, and the location for the heater hoses basically. I have replaced firewalls to make a correct non ac car but I would think some cutting, welding, and drilling, filling could get it done too? then ya need the non ac box. I would just get the non ac firewall and weld that in...done.