I agree with headers and improving the exhaust, but a straight pipe only makes noise, not power. Get a quality cat back. Exhaust stuff (including headers) for the '86-'90 TPI single cat application will get you what you need there.
Assuming this is an LG4, a better air cleaner than the stock single snorkel (dual snorkel is better than open element), and an upgrade intake manifold.
Replacing the carb is NOT on the list of things that will improve power. An aftermarket coil and ignition module are all the distributor needs (along with good cap, rotor, wires, and spark plugs, of course). | 
