You can't go wrong with good old Hella 500s.
Very bright.

Or the bigger 4000s like some run.
Lots of output if you have the room to mount them.

Another very good lamp to look at is the ones from Australia called Lightforce.

They get very high praises from what I hear, and a lot of Alaskan drivers swear by them.
You can also rotate the lens like you would a Maglite and change the beam pattern.

They come in 3 sizes.
Todd put some on his '88 awhile back.
Central 4WD by me carries these, and I can attest to the high quality of the construction.

I hope to give mine a good workout early Saturday morning if I can force myself to leave about 4:30 am.
Going to try and get some sunrise pics on Mt. Rainier in this same spot.

Corey