A lifted rig will look kind of funny with smaller tires on it, if the 33's are new or in good shape buying a set of new 31's can easily run close to $600. You can buy used oem diffs with 4.87's(proper gear set for 33's) from a wrecking yard for under $500, find used diffs on Craigslist.com, Pirate4x4x.com or other 4x4 sites for about the same, or get a set of gears installed in both diffs for about $600(bench work, double that if the shop pulls the diffs). The right gear set will be the most power gain for your money. After matching the tires and gears look to a header and exhaust upgrade along with an intake upgrade. An ignition upgrade will help a little, as well as running an electric fan. If this isn't enough power you can rebuild the engine, Enginebuilders.com has all the go fast stuff you want, most of which is smog legal here in CA. You can usually get about 145hp out of the 22r block and still have a reliable engine. There are also turbo's and superchargers available for the 22r, though I don't think anything other than an oem Turbo will pass smog here in CA.

Even with these upgrades the Toy wont perform anything near what you are used to(assuming your Mustang was a V8). For performance gains like what you are probably accustomed to you would have to swap in a Chevy 4.3(which fits rather easily), or swap in a Supra straight 6.