Yo quiero torque-o-bell!

Okeh, start with the basics. With 300k miles, it's likely your timing chain has some stretch, which will have retarded the cam, taking a big bite out of torque. Remove the distributor cap and turn the engine manually with the fan and belt in one direction until you see the distributor rotor begin to move. Then turn it the other direction and watch the rotor; if there's any discernible lag between your moving the engine and the rotor turning, the timing chain is slack and will want replacement. It makes sense at that time to do a super-careful job of getting the camshaft timed precisely to optimise your engine's operation for economy. Details are in multiple threads and you can be pointed at one if your engines appear to need this sort of attention.

Next, do a good tune-up. Tune-up parts and technique suggestions in this thread, carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download, and if you haven't done it in recent memory, it's time for a valve adjustment.

Next, turn your attention to the ignition system; see here (pay particular attention to the part about the source for new distributors with good advance curves). Until you gather up the $ and parts to do this, make sure your existing ignition system is in tip-top shape; remember breaker points start deteriorating the instant you first start the engine after replacing them. Try an initial timing setting of 5° to 7° BTDC.

Next upgrade to go for is a 2bbl setup. See here and here and here.

Dutra Duals are a terrific and very streetable upgrade, but it sounds like you're trying to contain costs, so those are probably not on your shopping list right now. So as long as the factory exhaust manifold is in good shape, wait til it comes time to put a new exhaust system in the car, then upgrade to a 2¼" headpipe at least. You can also run a 2¼" system all the way back. No need to buy an exotic muffler; just use a larger-than-stock, stock-type muffler (or something else, depending on how loud an exhaust you want).

This should be enough to get you started!