Leave the pop-ups and get a good HID set-up, there was group buy or something some time ago, I'm sure one of the official vendors can hook you up.
Like poodles said, the lights will be sitting to low to be effective, not to mention that pop-up lights are pure Supra and the idea of putting something else in destroys the "period charm" of the car.
Also, when the lights are retracted, the front end looks better than any conversions where the lights are always visable that I've seen.