No factory AC

My 74 monaco doesn't have AC.

Strangely(?) there is a blank where a vent would be on the pass side of dash. Talk about cost cutting...

I would like to add AC. Integrating it into the existing ductwork would be nice if possible, as I'm not a huge fan of the unit hanging under the dash.

What sort of options might I have for this? I realize this is not an easy undertaking.
Author: 74monacoHT