These are the ones that I poked into my rig. They are a huge improvement over the sealed beam, and there are gobs of aftermarket bulbs available for them as well.
Cost was about $75 for the pair. I did isolate them using relays for the high and low beams, I installed all new wiring for them, and used none of the factory harness when I made this swap. You can get new headlight plugs at the auto parts store, as well as the relays. I used #12 wire for everything except the trigger on mine. They function just like factory.
You'll notice a bigger draw on your alternator. They'll brighten noticeably when you accelerate from a stop. A higher output alternator is really your only solution for this. If you look for an alternator from a 94 GT with a 5.0, it should bolt right up to your existing brackets, and with a few simple modifications, you have 130A of power, internally regulated unit, and with the internal fan, it runs cooler.
DO NOT try to just plug some new H4 lights into your factory harness, it's nearly 40 years old, and not rated for the power that these new lights draw. You'll ruin something if you don't rewire. (switch, wiring, plugs, etc.)