I admire repurposing. All my lights so far are converted Marwi Halogen units.
Do you have the multimeter to measure the driver's current output to the LED? The Luxeons Pe2er and I have used can't handle more than 400 mA (overdriving red-orange LED's is bad= dead). It gives me about 100 lumens out the back. The CREE XP-E red-orange can handle 700 mA max and is about the same output. If you have to replace driver and LED you may as well build a new light and let the old one be. You could try a red lens and see what you think. That is not the way to build a red light from scratch, but it's an acceptable mod to a light you have. So what if you lost 50% of the output? You'd be the same place, about 100 lumens out the back from a very easy mod.
Seems worth a try.