I just went through this, starting with almost the exact same panel as yours. $35k in avionics later, it' s amazing. The entire portion of the panel in front of the copilot seat is now blank and ready for an ipad mini mount. The center stack is dominated by the GTN 750 with the new PS engineering 8000BT sitting above that, and the old #2 KX155 nav/com and old KAP 150 autopilot below it. I opted to put in the Garmin ADS-B remote mount, so it's controlled by the GTN and frees up panel space. I removed the old ADF, old GPS, old Com 1, old intercom, old KNS 80 rnav, old transponder, and old am/fm stereo. I moved the vacuum attitude indicator to the old adf indicator hole and put in a new G5 front and center. The new panel is so excellent and I got 12 extra pounds of useful with all of those old, heavy radios removed. Bonus! Good luck with your decisions.