Hey there. I'm in California. Check this out. It should help.
http://www.calguns.net/caawid/flowchart.pdfFor your question, if there's a detachable magazine, you cannot have a pistol grip.
If you keep the pistol grip, you'll need a bullet button. There's one company that sells a bullet button that can be adjusted from fixed magazine, to bullet button use, to regular mag release (no bullet required). I just got an AR lower (my first) to build, and I'll probably go with that type of bullet button. It can be seen here:
http://www.goldenstatetactical.com/bubucobne.htmlGood luck with the move!