The P/L & P/W wiring is contained within a single harness. The combined harness breaks up into 3 parts
1. The cross-cab section
2. LH door group
3. RH door group
The door harness sections are fairly straight forward - they contain the connectors that plug into the window regulator motors, the lock solenoids and the associated switches. They separate from the cross-cab section at a 2 piece connector (little one for lock and bigger one for windows) out near each door.
The cross-cab section has the connectors that plug into the fuse block and also the door lock relay. The windows have no relay - just the motors and switches in the doors.
The best way to do this is to hit the junkyards or watch C/L for someone parting out an 81 - 87 truck.
Neither the locks nor the windows is a complicated system - and could be fabricated - but it is so much easier to pull an OEM harness out of a junk truck. Since you already have fully loaded doors, the only thing you would need to do the job would be a lot of wire and the previously mentioned lock relay. But trust me - even if you have to search for a while - find an OEM harness to install.
There are 4 holes that need to be drilled - for the wiring to make the transition from the A pillars to the door shell. There is also a short rubber conduit that the wiring passes through as it makes that pillar to door transition. There is a backing flange for each end of each rubber conduit where the holes are located.
Placement of the holes is critical but even if your truck never had power W/L's there are marks on the A pillar where they are to be drilled - actually there are just little dimples where the mounting screws for the flanges (for the rubbers) are to go. Just use a step drill and make a 1 3/8" hole for the wiring bundle . Since your new doors are already equipped this doesn't apply to you - they are already drilled and probably have the rubber conduits still attached.
That is the entire scope of the upgrade.
One suggestion:
Once you have located the harness and before installing the new doors, run the wires out to the door components and test everything. Hook a battery charger up to both leads that would normally plug into the fuse block. Run your windows up and down and cycle your locks . This is only because its much easier to repair/replace door components while they are on the bench. Plus when you finally do install the system your will have functioning winows and locks from day one.
I am doing this as we speak as well, so if you have any other questions, come on back.