Consider this configuration...it might save you some money and and do everything (or almost everything) that you're trying to accomplish.
1. Ditch the expensive GTN 635 and go with the 625. It's about half the price of the 635 when you purchase it along with the G3x. If you really want a Nav radio as part of your system than a GTN 650 (GPS/NAV/COM) may be a better choice and more bang for the buck. I know a lot of people still like to have a NAV radio, but these days I personally don't put much value in them.
2. If you went with the 625 then you could add a second GTR 20 com. Unfortunately, they don't make a NAV/COM in this remote mount unit.
3. Go with the GTX 45-R with ADS-B (in and out) rather than the 345-R. You'll already have a WAAS GPS in your GTN, so you don't need another one to satisfy the WASS GPS requirement for your ADS-B (out).
4. GMA 245 audio-panel, not the 240.
5. Two GDU 460's...not a 460/465 combo. Instead, go with two 460's and add a stand alone GDL 51-R. The GDL 51-R will give you your XM music and weather.
6. I'm sure the GMC 507 is a nice unit, but you can perform all of it's functions within the the G3x screen. So if you need to save a little bit of dash real estate than you can probably live without the 507. If it were me, I'd maybe invest the 507 money into a G5. You can always add a couple of stand-alone LEVEL and TOGA toggle switches to your dash. To me, that emergency LEVEL button is the best part of the 507, but like I said, you can have a stand-alone momentary push button or toggle switch that'll do the same thing.
7. GMU-11...not the 22.
8. Add a GAD 27 and 29
Mark