AOC versus ex military equipment
You need to give some more thought to operating structure when it comes to ex-military equipment and AOC issuance. How are you going to re-register and/or support them. An ex military airframe being used for para-public or civilian use under a civilian issued AOC - very big concerns. I looked at this personally for AS355 'civilian' airframes used in a para-public/military role and the manufacturers baulked on any type of conversion/support - note these were civilian airframes.
There is a reason the 109E's are available. Currently there is a lot of excess inventory on the civilian register and you would be wise to look there. A philanthropist is looking for something that works as planned, not a minefield.