Wings is an excellent shop. Brady is very technically savvy and experienced. A transponder check is a no biggie but you should see what kind of field approvals they get for fire tankers and Air Tractors. Impressive with infrared cameras etc.
And they can do bench testing and repair instead of having to send stuff in for flat rate OEM repairs (up to a point). The waiting list might be long for installs, though. They have a large volume of repeat customers. But he should be able to squeeze in a standard transponder and IFR correspondence check.
(and a few more airplanes)