led night hunting light

I'm new to the forum and LED lighting. I'm looking to build my own "head" for my 21 volt coon hunting light. There are several on the market similar to this. An example can be found at www.valleycreekhuntingsupply.com and www.brighteyeslights.com. I plan on using a modified D size mag-lite bezel or something similar if there is anything on the market. To start with it will be ran off of a 21 volt nimh battery pack. I'm looking for 1000 to 1200 lumen with a tight spot with a little flooding and a long throw. I know I need a driver, regulator and the "bulbs". Other than that I'm clueless as to which exact components I really need. Any help on exactly which components I need and any other input would be great. Thanks