When you do decide to change the panel, start by doing LOTS of planning. Remember that no matter what advice you get, the finished panel needs to make you (and only you) happy. After all, you'll be looking at it every time you climb in.
I always favor round radios and the smaller 2 1/4" gauges. They take up less room and have the same wiring/plumbing as the old style stuff. Places like Electronics International and Wings and Wheels are a good source for these. As for the ADS-B, are you going to be required to install it? Or is this something that you 'might' need? If you are dead set on installing it, check out Sandia, Appereo, Garmin, and L3, for the 'all in one' ADS-B systems. If you think that you only might need it, you have the option of installing something like the Trig TT-22 transponder, which can be interconnected with other components, at a later date, to make up the ADS-B system. Round avionics take up less room, weigh less, and don't need a tray installed.
If you have any switches or breakers still up on the overhead panel, you might want to think about moving them down to the instrument panel and away from your fuel tank. And maybe add a master solenoid to the battery tray.
Others have different views so get all the advice and make your own final decision (Grandma was right!). And if you need help just ask.
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