You can use whichever set up you like the most. Or you can be cool like all the other 1st gen guys /forums/images/graemlins/peace.gif and get it off a 3rd gen Camaro/Firebird!
You can find em on ebay, I wouldnt pay more then $350 for one. How I did mine, (and what id reccommend) fina the whole car fhr cheap, I got one for 150 bucks, then strip it yourself, youll actually make money on the TPI converson instead of spending money!
Dont waste your time with a harness from the donor car. Everyone says the Painless harness is not that good, its fine. Its not worth an extra $250 IMHO just to have the harness wrapped, I did that for like 9 bucks extra, AND its a good quality harness.
If you have a radical cam then you might want to think about a MAF set up. If you want to run MAP WITH a radical cam, the vaccuum has to be over 15". When I got my chip burned they said anyhitng with less then 15" is REALLY hard to work with, I had 16" (which is basically at the limit)and it seems to run fine.