I use LEDs from here, the same place I get my pinball 6v and 12v LEDs from. I use prepackaged bulbs in the stock assembly and sockets. That's it, no conversion caps, extra diodes, or rectifiers needed.
I get some plusating at idle but with the red lense on, you can't really see it. All are very bright and the LED tailight is much lower wattage, it made my headlight brighter which was badly needed.
Why not get prepackeged LEDs, buy some sockets and make your own set up?