You can already upgrade to HID or H-4 pretty easily. There are kits available in FLAPs or online (ie e-bay) for the h-4 conversion, which is nothing more than a headlight lens that you can change the bulb in without changing the lens. Then you can buy a HID conversion which includes the ballast and the special bulbs- I think the h-4 kits are less than 50 and the hid (xenon) conversions are around 150. I have even seen projection style lenses in the diameter of the bulbs in these trucks. I think h-4 is plenty. HID probably requires you to upgrade your alternator to something with a little higher output.

'51 Chevy 1/2 ton w/'62 261, HEI, offy, fentons, dual carter/webbers, t-5 & 12 bolt posi