Jugs went through this recently. All the cables come off the control panel and go high off the controls place them as close as you can to the firewall up over the brake pedal. The two long ones which go to the heater box on passenger side. The short one which goes to fiber defroster plenum takes a quick bend down after going over pedal support. You need to try to get this installed before underdash wiring to make it easier but it can be done with wires in place. There is kind of a tapered nook at top of firewall. Try to get them to stay there. Otherwise the arms from wiper motor hit the cables as the switch for wipers is turned on and may force the cable sleeves at control panel to break apart. Then you will need to epoxy them back or get another set of cables.
Soak them in evaporust bucket if you have one. Spray PB or WD down the wires and get them lubricated and sliding in the sleeves easily. Clean as best you can the hinges at defroster plenum and heater box and PB/WD those shafts so they swing easily. If you don't do this now you will be taking the glovebox door off later. Defrost plenum hinge is much easier to do before console or gas pedal goes in. Once you make initial connections test at the mounted control panel. Install wiper motor assembly and then dash harness. Put dash cluster in hanging off wiring but leave it out of the cluster opening. You want to make sure the arms of wiper don't hit the cables. Add power and turn the wiper switch on. If no problems then disconnect cluster and start working on adjustments at heater and defrost plenum so you are getting full throws of controls from panel.
