If 84M is going to be partly retained by present owner, use Crusty. He's good. Just annual the thing.
Once he perceives he has a continued stake in the a/c, he'll treat you (collectively) well.
The best deal on the avionics refit is Flying Machine Company, in Texas (T82). They do the harness on your photographs and deposit. Install is overnight and it comes total to about 70% of Garmin retail. Pays for the trip.