I have an '87 with the 4.2L and like what was said above, the only vacuum lines that i have left are the vacuum advance on the distributor, and the big line going to the brake booster.
In order to do this mod, you have to have a manual cable for your CAD(center axle disconnect) on the front axle. And you should do a nutter by-pass, but you can read about those on other threads. Then you can throw away your stock carb and get a Holley 390cfm 4bbl carb and have a very peppy performing 4.2L.