Lots of ways, most cheap and easy.
1. Put about 4 more degrees of base timing in it. The stock timing curve is weak and needs a little help, especially if you are in the good habit of putting 93 octane in the car(honestly, it is like $2 extra a tank, don't be a cheap skate lol )
2. Get yourself an open element air cleaner. Despite popular myth about the temperature of air being oh so important, the truth is that if there isn't enough volume, the temperature won't make a **** bit of difference.
3. Lower temp t-stat and higher pressure rad cap. A little help to the cooling system can help you get a little more timing in the car without detonation and it will also make the cars performance much much more consistent.
4. Look on Thirdgen.org for the Throttle Body "Porting" information. It is a super cheap and easy mod that you can do to pick up some air flow. While you are at it, get an extra gasket for the injector tower and double them up, a little more space between the injector tips and the TB means a touch more airflow.
5. The biggest of the cheap ways to get power is to grab a stock LT1 cam. It will slide right in place of you stock hydraulic roller car, reusing your stock lifters and push rods. Just make sure you put on some fresh valve springs to make sure it stays together. To be extra sure the engine stays happy, a fuel pump with a better than stock capacity and some injectors from an LO5(350 TBI) will ensure that your fueling is all taken care of.
6. GEARS ARE YOUR FRIEND!!!! The stock LO3 was equiped with either a 2.73(auto) or a 3.08(stick) one legger rear. Find yourself a 3.23 or 3.42 posi unit from a Z28/Formula/Trans Am or just buy some gears and a posi and get them put in. More gear is always better, don't be afraid of 3.73's or 4.10's if you don't mind humming a little RPM down the highway. Mileage will not be dramatically effected regardless of what gear you go with and make sure you get the appropriate speedo gears so you have the correct answer when the officer asks if you know how fast you were going
7. If you do 1-4 a custom tune from JSPerformance will help a good bit with power and mileage, if you do number 5 I would consider stopping at Josh's for a tune an imperitive.
The other big thing to look at is maintanence items. Make sure you tune up, filters, and fluids are all fresh adn ready to go.
There are a lot of other little things that can be done to the car here and there to pick up the pace. Weight reduction is always a good one and it is free, but that is a completely different discussion.
A lot of people knock TBI, but it really is a cheap and easy fuel system to work with and you can easily make up the little bit of ground in performance between the 305 TBI and the 305 TPI with just a few free/cheap mods.
If you wanna know more just shoot me a PM.
-Tim