Changes in compression from the different head design, and the vol of air. Both are no big deal, if you can find someone to tune the car. The IV is limited sofware wise. The SCT stuff for the V seems to work well with mods, which is why the Mustang people, and others 94+ haven't had problems.
Heads, intake, fuel rail, you'll have to decide to stay distributor, or go the newer coil set up. With a distributer you will lose the EGR. Wiring connectors and harness will have to be changed/lenghtned, injectors, fab up some sort of intake tube, vacume line fab, MAF of some sort...are you a MAP car? May need a new hood, depends what intake you go with...ect.
1993 LX 5.0