Here is a link to a restoration of a heater box on a Hemi 1970 Roadrunner @ Sandy's Garage:
http://sandysgarage.com/current.htmlGo to week 136 in the left hand column for text & pics.
Classic Auto Air may can restore your OEM unit for you.
Several companies make aftermarket A/C systems:
www.classicautoair.omwww.hotrodair.comwww.vintageair.comTheir "universal fit" evaps will be much smaller than the OEM units under the dash. Classic makes the "Perfect Fit" models that look as large as OEM. It is made to fit each model car. It will use your OEM heater pass thrus for the A/C lines & you must drill new firewall holes for the heater lines.
I would prefer a "universal fit" style & go for electronicly controlled vent doors, to lose the vac or cable lines.
Vintage Air makes a great evap, the "Gen IV" with elect ctl'd vents & control panel.
Granted with aftermarket systems, your controls will not look OEM & you may have to mount the controls in a non stock location (maybe in an under dash panel or in your console). A compressor mount will be the next challenge. Shoot I never liked where Ma Mopar put her A/C Comps, smack dab in way of admiring a beautiful engine. Bouchillon Performance makes comp mounts for Sanden Comps, even one that lets you mount it under the alternator (will need an elect fuel pump to do that & the Sanden "Shorty" comp).
http://www.bouchillonperformance.com/BPEaircondition.aspMaybe this info will help.
John
