I would start with Larry and Liz Booher of Southfield Fuel/Heli_Prop. Larry is an A&P/IA. If for some reason Larry can't oblige, Liz will know someone who can (Liz knows everyone!)
I don't believe Heli-Prop has a web presence but lists email as [email protected]
The seller has recommended Western Aviation at KSFF. Anyone had a bad experience with them? The aircraft needs an annual and wanted to combine the inspection and pre-buy.