A/C Hose Routing?

66 is different then the 65 and earlier. The early cars had the "knee knocker" under dash evaporators. The 66 was the first year for the combination heater/AC unit up behind the dash.
Not sure on the 63, but the 64 had "dimples" below the blower motor and somewhat toward the center of the car. There is also a dimple, lower then the others, for the water drain.
Here is a link to pictures of a add on system. You might be able to see where the lines go to the firewall. I did not use gromets and put the rubber hoses thru, but used bulkhead fittings. This is a 64 Valiant.

http://www.slantsix.org/forum/viewtopic.php?t=33267

PS: What type compressor, and mount are you planning on using?