AC vents connected to kick panel vents

[AirSpeed]

I discovered my 72 GMC used to have AC, someone filled the dash vents holes with Bondo and removed all the AC parts under the dash and replaced them with a regular heater box. I cleaned up the holes and bought new AC vents to fill the holes instead of trying to weld steel in the dash and smoothing it out. I am thinking of connecting the vents to the kick panel vents via a hose and a panel that covers the kick panel opening. Have any of you done this, if so how did it work? I am also thinking of connecting the dash vents to the heater. I dont want to have the vents in the dash for no reason.
Thanks for any suggestions! Aaron