Thanks everyone for the feedback. I am convinced (again) that TT21 is
the best option. I will make sure I build the harness with the wires
for the GPS input and ADS-B out just in case. I will order one along
with the L2 antenna. I had great success with it in the previous
installation and they are so easy to install pretty much anywhere.

Now if I figure out what to do with the flight computer, I am all set
for redoing the panel layout and getting to work


Cheers,
Morteza