Vespa electrical question

I'm posting this on behalf of someone else, I don't know anything more about it, but can get more info if you tell me what questions to ask. I was hoping someone here could help.

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question about old style voltage regulators:

I have this Vespa scooter which needs 6V to run the headlight taillight, etc..

I'm getting about 5-25VAC off of the stator from two wires.

I bought a bridge rectifier, which turns this into DC pulsed voltage. I also
built a 6V regulator which supposedly could handle 10 amps of power.

Well, I smoked that thing nearly immediately and need something more heavy
duty. The scooter has a negative ground, and I'm wanting to delete the
battery.

If I were to get a new old stock negative ground 6V regulator, how would I hook
it up, so I could feed in supply voltage (ac or dc.. doesn't matter) and
regulate it to under 7.5V ??
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