The used auto tranny will not be worth much. Not very many people want them. I still have the auto from the swap I did and have been trying to sell it since last fall. Yours will be worth a little more as it fits a 22R, (mine came off a 3.0) but I have gone as low as $50 and also offered to just trade it for other parts and I still have it.
About your other question on parting out the 84 after you use it as a donor. If it is a pretty solid vehicle body and interior wise, I would try to sell it whole. Lets say you start parting it out and sell a door, the seats, one diff and part of the dash or something. Then you have got very little money out of it and don't have a complete truck anymore. Sell it whole for $1000 and skip all the work. If it is a rust bucket of a P.O.S., then parting it out may get you more money. I have parted out a couple of vehicles. It is quite a bit of work and it takes time and room.
I think it is best to base your decision on what you want for your rig when you are done. If you can sell left over stuff and come out, great. Don't base the decision on how you will come out better. Decide on what will make you the happiest when you are done.
