Newbie 94 GT conv project

Agreed with nmcgrawj - an Explorer 5.0 has upgraded cylinder heads and a better intake, so you're getting power upgrades at the same time.

For a fox engine, the long block (engine from the intake manifold to the oil pan) is basically the same engine. However, to clear the electric fan you'll need to use the 94-95 accessories and water pump.

For brake upgrades, get the 99-04 GT front brake calipers & brackets. They use the same brake rotors as the 94-98 GT, but have two pistons rather than one (which translates into more braking power). You'll need to grind off part of the spindle (the part the brake bracket mounts to) to clear the slightly wider calipers.

You can get 94-04 wheels, they will all fit just fine. However, you may get some rubbing on the front if you use a 9-inch wide rim - really depends on the car. I believe 05-09 rims will fit on out cars if you use a 3/8" spacer.

Frame stiffeners are not required but will help you to put your power on the ground. Otherwise, the chassis will twist and flex and the wheels won't get as much grip as they could. I personally don't think subframes are necessary until you start adding power to the engine, but they certainly wouldn't hurt.