I can answer some of that.. first off, the 5 speed you have, is granny geared, you'll just hender performance b/c you are shifting constantly. Get the 6 speed if you want something to pull that thing around good and have a good street truck geared ride. Also, if you do, get a good clutch, like a STAR or SPEC, centerforce clutches suck. You need a new clutch b/c of the extra weight from the stock ls1 to the truck. The stock clutch is made for 3700-3800 lbs car, not 4k+ truck.
You'll need to make your own mounts or pay allen (farmtruc) to make you some. You wont be able to keep the a/c unless you cut your crossmember some to allow the clearence. The 94 and up gauges work with the stock ls1 sending units, but i'm not sure about before that.. no one has tested to see.
On the full list, i'll let someone who has actually done it, tell you that, but i know you need custom mounts made up.
91 s10 - bagged and bodydropped...getting rebuilt
91 nissan - backhalfed and bagged