Charging system and other wiring change help needed

Bringing back an old thread because I am changing to a one wire GM style alternator with internal reg vs my original hot wire and field wire. My instructions say to eliminate the voltage regulator buy cutting and dead ending the wires going to the regulator. Then run the one wire from the alternator directly to the battery with a 200 amp fuse in line. Since the battery is in the trunk could i run my one wire to the starter relay instead? I will include a pic of my wiring diagram that I am currently wired to. I havent crawled back up under my dash yet to verify my wiring as to where everything runs. I have moved all my wiring and componets under the dash so there are no wires in the engine compartment. Bad thing is I did not make a custom diagram as I went so I need to pull and chase and verify all wiring to be sure.
Another question I have is I still need to hook up my voltage gauge. Where or what wiring would you tap into for this?
Thanks Rod