re-wiring a 69 Dart

One thing I will note, the kit is NOT built to run the factory alt and external voltage regulator. It's intended to use a 1-wire type alternator. Instead I went ahead and did the toyota upgrade and simple added a keyed 12v excite wire and sense wire. I discussed this with AAW and their intentions were to add it to the harness

I'll call them up and mention this to them before I buy the harness. How about an aftermarket sound system? Will the harness support that?