I decided to go with the gray, but as if it was a hasty overspray of the normal IDF sand-gray, so I took some Humbrol buff and a couple of old brushes, and worked the Humbrol into the nooks and crannies that might have remained unpainted or poorly covered during a re-spray. I then used a thin black acrylic wash on everything, and pin-washed bolt heads and such.
Tracks are temporarily fitted, next is a gloss coat, then decals and detail painting, and I'll finish with dust. Pics so far: