okay, so engine all rebuilt which turned out great, so just replacing the loom and tried to go for a simple no battery loom... bought this one off SIP...
https://www.sip-scootershop.com/en/product/wiring-loom-217897-vespa-px80-200e-lusso_86100000
...but just ignored the "w/o horn rectifier" which I probably should've looked into a bit more? maybe?
So ran the loom, changed stator over from 5 wire to 2 wire, I can see that indicator switch is different, uses a later model switch, 6 wire instead of 3 wire and also the ignition barrel is a 2 wire instead of the 6 wire installed as standard.
So all that is okay as I'll just get a new ignition barrel and indicator switch, my question is about the horn, so there's only the one yellow wire coming from the switch, is it just a matter of hooking into a 12V source coming from the regulator and having that feed into the horn?