I am working on a 73 duster for a guy & its an A/C car. He want to convert it to a non A/C car. He wants to find the section of the firewall where the heater motor & lines come through & cut that out & replace it with a non A/C cars firewall. Seams like alot of work. Has anyone done this ? Is there an easier way ? To me thats a lot of cutting, welding & body work.