I just spoke with Al Gester of EAA Chapter One, Flabob airport. Al is responsible for the Wathen Foundation's restoration of an old SA7 they found hanging in the rafters. All the work is being done by school kids with Al's oversight.
I asked Al how to best clean the dust and dirt from an old plane. Here is what he advised us:
1. Remove all cowlings, covers, inspection plates, etc. Record and mark these so you know where to replace them later. Take pictures as you proceed.
2. Blow off as much dirt as possible with compressed air, but taking care not to overdo things as it will only result in a cloud of dust that will resettle on the airplane.
3. Next, use soft, slightly moistened cloths to wipe of any remaining dirt.
4. Do the above outside to keep the dust out of the hangar and so that any remaining moisture can quickly evaporate.
5. Move the plane into a hangar and go over it closely with a flashlight, recording any areas where repairs or replacement might be necessary.
6. Coat all wood components with Stits wood varnish to protect surfaces.
7. Engine - seriously consider an overhaul if you are not familiar with the recent history of it.
He mentioned that he once had the same O-290 as in our engine and only had good things to say about it. According to Al, when the ground power unit O-290-G4 is converted back to an airplane engine, its designation is an O-290-D. See more on the engine here:
More on Gester's project At the links below. He seems happy to help us, and he knows his stuff.
Al Gester, EAA1, Wathen Foundation, www.flabob.org (Al does not do email)
951-683-2309 (weekdays 8-3:30), firstname.lastname@example.org