For crap 6V lights, try using a 25W/25W 6V bulb - it produces a much brighter light than the 35W/35W 6V bulb that you're usually sold.
I fitted the 12V ac electronic kit to my Li from AF Rayspeed, using the Li crank. I chose the mid weight flywheel and it works really really well. If you buy an electronic kit for an Li crank, make sure you get the pick up and the flywheel prong things properly aligned.