Good info @Ex850R - I might come back to the centre speaker idea, depending on what it sounds like. In the previous V70, even with the standard speakers, the SC901 headunit and no centre speaker, it was way better than the Focus XR5 stereo, who was 9 years newer.
I'm digging through more boxes of parts at the moment, mixing and matching bits and pieces for the best interior I can put together.
I've got heated seats wired and working now too. I had a new genuine Volvo coin tray surround (which the switches mount into) and found some used switches in my stash of parts.
Found a decent lower column surround too but not an upper one yet.
I'll repair the passenger side lower dash today and get the glovebox back in.
Drivers side can stay off until I plumb the boost gauge.