Need advice with first project

Hello,
I am a longtime Surefire owner and recently got hooked on LED illumination. I am about to build my first light and have a couple of questions. I have an old Magcharger that I never use anymore that will be the host. I would like to put a Carley reflector, 5W HD emitter and BB750 into this light. I am very skilled mechanically and electronically, so I don't expect any problems with fit, function or heat management. My questions are: Do you see any problems with this combination before I get started? Is there anywhere I can order a W3 or W4 and get what I order? (I really hate disappointments) I'm not too concerned with it's efficiency as I'm working with a large, rechargeable power source. Thanks for any advice you can offer,

Jeff

Is the voltage on the Magcharger gonna dance with the BadBoy? Will the batt be able to keep up with the drain? I'm asking because I don't have a Mag Charger. If the Voltage is close enough, you may be able to direct drive or even just use a resistor.