Bad info above.
Different brands of bulbs vary slightly in wattage, so this is all approximate. Remember that the late TW elecrtical system is designed around a load balanced with output. It is important to maintain this balance when swapping around lights. There is not enough "extra" electricity for adding significant lighting. Therefore, to do significant upgrades to output it is necessary to convert to High Intensity Discharge or LED lighting, or some combination thereof. Since it is customary to deal only with watts when doing anything with transport wiring other than calculating wire size, I'll speak only of watts to keep it as simple as possible. The wattages of the first 3 bulbs listed below come from the shop manual supplement for late model TWs, so they should be considered correct.
Late model TWs have a 55/60 watt headlight.
Tail and front markers are 8 watts each, total 24 watts.
The 194 speedo bulb draws about 3.4 watts.
The typical 756 high beam indicator draws 1.2 watts.
Total amp draw in neutral with the high beam on is about 87 watts.
Brake and turn bulbs, along with the other indicators, are intermittant and really don't need to be worried with because they are never on for long.
So, we have 87 watts with which to play.
How does 3 times the stock light with the stock pattern sound to you? Suppose we go to a high quality Japanese or German HID conversion for your stock H4 headlight? Don't buy a cheap conversion, you won't be satisfied. Shop around and you can even find a conversion with a waterproof ballast.
HID conversions come in 2 types and a wide range of color. It is critical to pick the right conversion or you'll have a ton of problems. Let's look at type first, then color.
The first type is HID on low and conventional halogen on high. Presumably, the low beam is so much better you'll never run high, but it has to be there to appease the government. You'll have to rewire the headlight so low does not go off when you flick high for the roadside inspector, because it takes a little time for the HID to relight. Flip from high to low on a dark road, and for half a second you have total darkness. Plus, you can't really run high beam and HID low at the same time due to excessive heat build up. Also, lighting them up is what wears out HID bulbs and causes them to fail--they'll run darn near forever if never turned off.
The second type of HID conversion, sometimes called bi-xenon, uses HID for both low and high beam. Either a shutter moves near the arc to reflect its apparent location to approximate the location of filaments in an H4 bulb, or an electromagnet moves the actual arc between the high and low beam filament locations. You'll want the type that actually moves the arc. These pattern much better in reflector housings like the TW's.
Assuming you've found a source of a good quality HID conversion with a bi-xenon bulb, you'll next need to pick the color. Avoid the temptation to be a showoff with the blues and purples. Nothing labels someone as an idiot faster than bright, glaring lights that don't really show up the road all that well. Pick a clean, white color, somewhere in the 4000 to 4300* Kelvin range. This color closely replicates natural daylight, shows up all colors of obstacles in the road, and does not advertise you basically are running an illegal headlight like to other colors do.
Installation is an easy step-by-step process that does not require cutting and splicing wires if you have a quality kit. Pretty much plug-and-play, except you'll need to rig an on-off switch for the headlight for when the electric start is being used. You now have 3 times the illumination of your stock headlight and a bulb that will last 2 or 3 times longer.
Unfortunately, your HID conversion only draws about 42 watts. Your stock headlight draws 55 or 60 watts. Not really a big deal unless you don't like overheating your battery and boiling it dry. You could easily add a 4 to 6 extra taillights for improved visibility and to rebalance the electrical system. You could also convert all your stock lights to LEDs and darn near have enough electrical power to run a second HID headlight. LEDs of equivalent light intensity draw about 1/10th the power of the stock bulbs. Switching to LEDs will free up about 25 watts, which, along with the 18 watts saved by the HID conversion, results in 43 excess watts, just the right amount to run a 2nd HID headlight, and project 6 times the stock illumination on the road.
Of course, if you don't want to spend all that money and do all that work, just pick up a Sylvania Silverstar Ultra H4 halogen bulb. Same wattage as stock, but much more efficient in making a brighter, whiter light. About $30, and well worth it. No, it's not as good as a dual bi-xenon HID conversion or Truck-Lite's DOT approved LED 7-inch round headlight (which is on my wish list), but it also is $250 cheaper than either.