I wouldn't go paying too much for that trigger housing. You can get complete packs for $75 some places. I think 20 is the most I would pay for one myself, unless it was already clipped and pinned or something spectacular. I have never seen a sidefolder on a G3. Might look a little funny. I have seen some stocks that curve like the MP5 A3 tele stock does to fit on the shoulder better than the old style G3 tele stock did. Have you thought about that?
Congrats on the new gun btw! Lets see a photo