if you want to re engineer a bike please do. you need a plan. there are many ways to deal with ac 6v stators. half wave, full wave modified stator, floating a new ground off the frame. either floating or half wave requires no stator mods.
already posted but this is how you float using the kbpc5010 rectifier. you do not use the taillight tap it's n/c.
rectifier + ------ cap +
rectifier ac --- stator wire, blaster type ac regulator +
other rectifier ac ---- n/c
rectifier negative -- new floating ground. it floats at -7v.
frame -------------- blaster ac regulator -, cap -
14v rectified and regulated juice is between the new ground and + on the rectifier.