SIP Speedo on a fully DC vespa

Hello,

I'm re-wiring my ET3 from the ground up to be fully DC (even the horn) using a 12v PK FL stator and a DC only voltage regulator (no AC out).

Where should I hook the brown RPM wire?

and.. do I still need to use the Powerbox?

Thank you!!

I got the same problem on my vespatronic 12v?