The late and not-overly lamented Cabair used to have a fleet of Grummans which is why there are quite a few around, which went into the private market when they replaced their fleet around a decade ago. It's probably also why most of the UK AA5s are very well equipped.
A typical fit is 2xalt, 2xVOR, ILS, ADF, DME, 2xradio, and a useless single axis autopilot.
Some very good advice there from Dan, although if the syndicate are all high hour glider pilots, the bit about a trigear Europa is probably less important.
G