There is no use in converting banshee headlights to LED because the reflector doesn't match the light source.
Besides that, any LED kit meaningful enough to consider in the project is going to wind up costing just as much as buying an LED light outright, or you're going to wind up with a dim light and a crappy pattern.
It's akin to shooting yourself in the foot.
In the world of lighting, input power supply is only a concern if there isn't enough, or if the voltage exceeds the light's specifications.
You can wire up a 5W light to a thousand truck batteries capable of producing megawatts of power, but the light will still only draw 5W.
So long as your voltage regulator is operating properly, you won't have a thing to worry about with extra power.
ChrisG also sells some smaller lights that are still much more powerful than banshee lights.
They're rated at 1280 lumens, about like a single car headlight, draws only 16W, and costs $50.
Banshee lights don't come close to car headlights, and you can mount them on your shocks just the same.
They come in spot and flood, they've already been tested by Dezsled and work great.
If you wanted to get two, you could buy one in spot and another flood, or two spots, or two floods.
http://okledlightbars.webs.com/apps/webstore/products/show/3601275http://okledlightbars.webs.com/apps/webstore/products/show/3445191If it's just for looks and a few night rides, go with some cheap banshee lights or halogen bullet lights and forget about LED's.
Banshees and LT's have been riding at night with only stock lights as illumination for 25 years now, no reason why they won't work for your application.