Regulator/Rectifier Install

I've got a new harness and reg/rect. combo and would like to wire it up to my '78 SE. I've searched the forum but haven't found an answer that makes it clear to me, although it's probably just my thick skull. I purchased a reg/rect identical to Mikes XS #24-2089 (ordered in canada through XS650Direct) that should work with my grounded brush. I'm confused on the wiring since the stock harness has 8 wires while the reg/rect has 7 out. it looks like the redundant one is ground, so does that mean I can just wire it to one of the grounds in either plug that went to the stock regulator or stock rectifier?

Thanks for your help, i'm getting antsy since i'm so close to getting this thing going but i don't want to screw this part up since i might only get one chance before I wreck some parts.

Yes, your new unit shares the ground wire for both components inside, so just pick one from either original harness plug.