I'm not expert on them, but I have done some research.
First off since your vehicle is a 1990 Land Cruiser you have sealed beams and you'll need to a conversion with something like this:
Which can be had all around the net, I suggest checking a Toyota Land Cruiser forum to get the sizing and everything. When I had my Blazer I bought everything under the sun from Stylin Concepts, now Stylin Trucks. Here's a link to the lights.
http://www.stylintrucks.com/sn.aspx...at_-26|181=Headlights&canned_results_trigger=
Most of the kits use an H4 bulb but it sort of depends on sizing and what not. This will help your visibility issues out quite a bit.
From there you can use a whole host of bulbs to increase you visibility. HID's are tricky though, if you don't do them correctly you'll end blinding other motorist and have reduced visibility. Go for a kit with a colour temperature of 4300-5000K this is close to natural light and will give you the best visibility. Anything more gets up into blues and purples which are pretty much useless at night.
This will show you the different colour temps and how they output.
http://www.shopxenon.com/vi_60.htm
If you are going to run HID's I would also recommend getting yellow fog lamp bulbs as well, Hoën makes an excellent pair. This way when it's raining you can get some contrast to the HID's which reflect weird.
I would go the normal halogen head light route though as it will be cheaper and more on the legal side (I don't think any HID aftermarket kit is legal). You can get Silverstar sealed beams which are number H4656ST for the lows and H4651ST for the highs.
I would probably do the sealed beam conversion and then get a good performance halogen for it. I would say avoid normal Silverstar bulbs as they burn out quickly. I believe H4 bulbs are the same as 9003. Phillips makes the brightest DOT legal ones you can buy called X-treme Power.
If you have any other questions I can try to answer them for you.