I used 5mm LEDs but I'd strongly consider 3mm's as they would be much easier to work with, both with preperation and installation, and maybe work better for general use, I've had to screw around to fix some problems I've had.
http://www1.jaycar.com.au/productView.asp?ID=ZD0132Thats a 3mm Blue 3,000mcd LED. I used a 4,000mcd bright one, some people say its too bright but I'm fine with it, so 3000mcd might be ideal and suit you better. Just have to pickup some resistors too, only about 40c your looking at (For around 8 ). I used 510ohm's, but as Blue LEDs use more voltage you'd need a resistor with slightly lower resistance. That, some wire, heatshrink or tape, and soldering tools

I just don't know if 3mm LEDs will light the needles as good as 5mm ones do.
Personally I'd only have lit footwells which come on with interior lighting. I enjoy being immersed in darkness at night, rather than sitting in a bright glowing thing of light. Thats why I don't like Reverse guages - theyre too distracting, having giant white circles in front of you. I hate driving at night with oncoming traffic also, it's just, toooo much light! I love my red dash though, it's more subtle
