Richard,
I have been using Carter Aircraft in Sebring . They have done my annuals for the past eight years and are now quite experienced with Commanders. If you want to stay closer to home go to Boomerang Aviation in Hwo, North Perry, in Hollywood. The owner Tomo has owned a Commander in Australia as is very experienced working on them.
On the other hand stay away from Miller Aviation at HWO, he's a butcher.
Bill O'Neil