You might look into the O-360 Lycoming for this airplane too.
The XP-360 is a lotta bang for the buck.

If it were me (and it almost was), I'd do the O-320. You don't have
enough tanks on the -9 to properly feed a -360, and you don't need the
extra weight. Plus, the -9 has enough wing that you don't need a ton of
power to drag it into the air.

Ed Wischmeyer