Few things after the initial tune up (since this is your first carbed car, do lots of reading!), apologies if this gets long but it will help:
Wash the engine bay, or do a major cleanup. Seriously, the car will look much more presentable. A pressure washer is recommended, but degreaser and a lot of wipes will work. If you choose the water method, cover anything electrical (distributor and wires etc). Remove the carb if you can (not required but helps) and cover the ports on the intake. I believe this is a 2 barrel engine, so there will be 2 holes on the intake. More on this in the next paragraph.
When you change the carburetor, change it to a 50 state smog-legal 4 barrel carb, not the 2 barrel. This will help performance, and since the motor is already poop from the factory, it might run nicer and gain gas mileage if you keep your foot out of it. Since you are converting this, the intake will also need to be changed to accept a 4 barrel carb...they literally change the amount of ports, but it's otherwise a bolt in change. It also needs to be 50 state legal, and I believe the Performer RPM is. When you buy a carb, because you are new, I would recommend one with an electric choke and vacuum secondaries. What an electric choke means is that you won't need to worry about cold start stalling unless it's improperly adjust; directions come with the carb itself. Basically, it regulates engine RPM and heats up the fuel before it goes into the cylinders. You should also prime the carb before cold starts, simply tap that gas pedal once or twice to feed fuel. The vacuum secondaries are the other 2 barrels of the carb that are quite literally, secondaries. There are 4 barrels, the main 2 are your primaries, they are what keeps the engine running and open under a certain RPM. There are 2 types of secondaries, mechanical and vacuum. Mechanical you don't need to woryy about, they are pointless on a street engine, even moderately built engines. Vacuum secondaries open at full throttle when the revs rise high enough that there is enough vacuum from the engine (the force/rate at which the engine sucks in air per minute or CFM) to pull them open. This stuff will make your life much easier.
As far as that motor, EW
Look at all that garbage you can rip off there
Get rid of that air filter kebab. Throw it right in the garbage. It's no good, I find them to be pretty restrictive. Personally, I think you'd be better off with $15 open element, plus, it looks cooler but it'll totally stand out against all that grime.
Another thing to do: Check all the hoses. All of them. Make sure none are old and brittle, If they are, replace them. This will pretty much defuse any potential small vacuum leaks you might have or can develop in the future. Vacuum leaks will, not matter how small, cause a many issues like a rough running engine or a loss in MPG's.
With the better ignition it should burn a tad cleaner and better so I think you might pick up 1 or 2 MPG's. The engine should run a tad smoother overall too, and like I said, you might notice some small power increase, but if not, you should notice at least a bit more bottom end torque and a smoother feeling engine through the RPM range.
While you've gotten into the ignition system, another thing I would do is rebuild the stock distributor. GM's HEI stock distributors are pretty good...when they work right. That car being entirely stock, I believe with no doubt in my mind that the parts are worn out inside and are causing a loss in MPG's. You'll probably gain a few of those back and some engine grunt, and they aren't too hard to do. Once you put it all back together with new internal parts, you probably won't need to do it again for another 150k miles.
This engine can be built to rev, but in stock form, don't bother revving past 4,000rpm because power dies off at 3,800. If you ever really get on the gas, you'll notice this. It's pointless and won't do much good for the engine until you tear into it (if you ever go that far). Top end parts such as heads, cam, valve springs etc will bring your useable RPM range much higher. Stock heads flow like garbage, so that really limits the potential.
I'd also check to see if the rear axle is a Posi unit or not. If it is, it will make your life easier on the track since bother wheels get power without a one wheel peel or one tire fire when you punch it. The power will be more evenly distributed and it'll feel like it's got more balls. Converting it isn't too bad if it's not but I'd be willing to be it isn't. Simply spin a rear tire and see if the other side turns the same way. If not, then it's not a posi rear. Posi is a type of limited slip from GM by the way. Also, another way to make the car feel like it's got some balls is to change the rear gears. I think at best this car as a 3.55 rear and that's pretty standard. Changing to 3.73 or higher will get torque to the ground quicker but your RPMs will rise a bit at highway speeds and could potentially hurt gas mileage.
(Now hurry up and wash it and take more pictures)
