im not an expert or real mustang smart as half the guys in here, but ill get you started with what i can. im sure youll get some real good help in here. ok,some questions to consider: what do you have on it now? is it all stock? whats going to be the use of it(streetable,drag race,etc)?
my suggestion would be to start with some basics, get headers, aluminium intake, upgrade your carburator i reccomend a Holley (maybe a 650 double pumper). replace your stock cam, i say go with a Comp Cam (research which size/duratrion is better for you). next i would suggest a trans pak/ shift kit improver(like a B&M). after this, any $$$ left over you can use to upgrade other stuff like maybe a better distributor/coil,wires,plugs, maybe even replace your fan with an electrical fan. good luck.