Here is some info on upgrading the headlights.
http://lighting.mbz.org/tech/
has all the info you need to do it and get REAL headlights.
They have the european coded lamp housings, they aren't cheap. You get bright lights that don't blind on-comming drivers, and they don't reflect off rain. They were well worth it to me.
If you want the over watt bulbs you must replace the wiring. If you check most older cars they aren't getting full voltage to the headlights because of the resistance in the wiring and switches. Mine was dropping about .65v between the battery and the headlights before I upgraded the wiring.
To install a relay kit you just use the wiring going up to one headlight now to switch the relay on and off.
I brought two new wires up from the block behind the battery for power to the lights and mounted the relays on the inner fender pannel on the drivers side. The biggest job is replacing the wire and sockets to the headlamps. You must get 3 #12ga wires through the lamp housing pivot, I used WD-40 and worked them in. It's about an all day job to do everything and dress it up neat.
You could use the stock watt bulbs in the e-coded lamps and have good results. With the upgraded wiring I'm running 100/130W bulbs.
I checked the current draw with a clamp-on amp meter and they draw about 19amps on low beam. Put those bulbs in stock wiring and it would blow fuses and melt down everything.
Any one want more gorey details just ask.
JS