I can tell you what I went through on the 87 sammy I picked up last year. It, too, had been sittin for a couple of years when I bought it.
First thing I should have done is drain the gastank. I had carb trouble from the start, and I think some of it had to do with the little bit of gas that was still in the tank. I ended up replacing the carb, I found a rebuilt one on craigslist that was far cheaper than having mine rebuilt.
I replaced the shifter sheets right off, didnt want to have that problem.
The front wheel bearing were pretty bad, had to replace them. Wish I had done the axle seals while I had it apart, because I now have one that is leaking and I am going to have to tear it all apart again.
My cat converter was shot, had to replace it to pass smog.
That was about it, other than the routine stuff (oil, plugs, wires, coolant etc). The $700 I spent on the sammy ended up closer to $2500 by the time I was done. Still, I love this little truck, and had a blast fixin it.