Are you removing the AC unit all together or just the duct wok in the headliner? I removed the duct work from the headliner and just ported the air with a piece of 4" aluminum flex pipe out the speaker hole then installed a 4" RV adjustable vent on the back pillar, blows all the way to the front windshield. Works great for the dogs!

 

You will need to remove the wiring harness to set the fan speed and to turn on the A/C, remove the A/C system and lines, and as for the vents you already have that part figured out. You could look at the Rave manual and just split the harness from the donor truck and just remove the wiring circuit that is needed and route that to their required locations oh you will also have to route power for the A/C circuit to the fuse box out by the battery if you want it factory but if you just want to rig it run power to the back as if you were installing a car amp power kit fused, run at least 4 extra wires from front to back, one for on fused, i believe its two for the fan speed need to look at the Rave manual but it's doable either way.