I have always run H4 housings on all my trucks. The rectangle type you can get for like $12 and up on eBay, I usually go for some nicer ones a kit 25-30. Then get some 6000k bulbs, or as close as you can find. H4 bulbs have a hard time going past 6000k. That's when true HIDs come into play

On my 78 I spent about $75 to get (4) 5-3/4" housings. The are really nice, but were deeper than my core support would allow so I had to open up the wire hole on the back a bit with a cutoff tool. The 78 also only has 2 low beams, but 4 highs. My outer pair of bulbs are about 4300k, so kinda yellow. Inners are 6000k. Going from low to high goes from normal yellowish white to a blueish white. I did buy an HID kit that's high/low ballast with a dual filament bulbs but I wasn't too happy with them. So I put them into my ramcharger instead.

Wiring wise, its a direct swap. I also have always run the diamond reflector style with a clear lens. I think it looks better during the day and they work pretty great at night.