Like minds think alike: I just finished rigging up power to an old Bell light and it works great! Plus you get some side-lighting from the diffuse beam it casts. I have a small battery powered LED rear light, but it looks like the batteries are going to last a long, long time. So for now I'm just powering the Bell front light, which I made removable by putting alligator clips on the end of it's power cable and leaving a small looped cable tie on the frame that I can easily feed the alligator clips through.
I had to buy replacement bulbs and after trying a few, I found the 4 Cell Maglite Kyrpton bulbs to work perfect. I did set my spark plug gap to .024 and I upped the iddle a tiny bit. When I was testing bulbs, sometimes just touching wires to the end of a bulb would cause the engine to quit. I found I needed better connections and I ran a line straight from the white wire and another from the frame instead of testing using the black wire which runs all the way up to the kill switch and back (adding resistance along the way).
FREE LIGHT RULES!
Mark