With that kind of budget, Id recommend the things I did when I first got a car.
Dual exhaust can be done on a budget....I love dynomax turbo mufflers and at 31 bucks apiece, theyre a deal.
I'd read up on ignitions, especially stock ignitions and make sure youre getting the most spark out of your system, at the best time throughout the rpm range.
I doubt you have posi......understand that many factory steel wheels can take up to 245's, and that with cheap traction bars and adequate shocks can help off the line traction.
Dont use an air filter that is filthy or one of those 9" or smaller diameter ones. Make sure the fuel filter is in good shape.
Learn the correct way to set the carburetor's idle mixture so you dont foul spark plugs. Make sure the carb is clean and doesnt need rebuilding...BTW, odds are thats a motorcraft carb; theyre really easy to rebuild.