If cost is not an issue, I would consider the big front brake kit from Stoptech.
http://www.buybrakes.com/c-102_lexus-lx470_big-brake-kits.aspx
Slotted rotors and good pads for the rear could be purchased at the same time.
Stoptech, Power Stop, Power Slot, Brembo all make rotors for that truck. EBC and Hawk make good truck pads. I would poke around on their websites and try to decide for yourself which compound would be the best fit for the type of driving you do.
As I mentioned earlier, I use the Hawk blue pads on my smaller trucks and Hawk or EBC red pads on my daily driver. The blue pads cover most driving conditions and are better than stock pads for performance. The red pads are far superior in the performance category, but make noise and wear out rotors. I don't care about the noise, but you might.
For clairification, my daily driver is a newer Dodge Cummins 4x4. It weighs quite a bit and I tow a lot through the Sierra Nevada mountains, so brake performance is critical.