The first headlight upgrade should be the installation of relays, regardless if you change to hi-tech bulbs or keep the originals. They make a huge improvement in light output. Here's a link explaining how I did mine:
http://67-72chevytrucks.com/vboard/showthread.php?t=387693&highlight=headlight+relayI run halogen hi-beam bulbs but regular sealed beams on the low circuit. Halogen sealed beams burn out faster than any other bulb on the market, and I run with my lights on all the time. The halogen high beams don't get used near as often so they last a reasonable amount of time.
