I got busy installing, and low and behold, what do you know? Once I had everything in hand I was able to determine that I could actually install the items the way I had intended originally.  That had the Autopilot head on top and the G5 on the bottom.

In talking with Steinair and several other people the consensus was the limited space for the two center instruments which are constrained by the hole in the secondary panel, would not leave room for the G5 on the bottom. In turn, the AP head would block the canopy release hole. The release mechanism itself is the reason for the small area through the secondary panel.

However, mounting the two center units as high as possible left room, but not much extra for the G5. I then experimented with the release mech and found it will work fine with the hole lowered just a bit. So I mounted the AP unit as hight as I could and drilled a new hole for the canopy release handle. I will make my own handle and intend for it to only be installed during aerobatic flight while wearing parachutes. Otherwise it will not be in the plane.

Add a flap switch and ELT panel and the center stack is mostly complete.

Cut a hole in the left side panel blank and mount the PFD and most of the panel instruments are in place.