Will check that through. I started working this out last year, after the info about the Sierra Leone almost-copies came through and suggested it might be solvable (those blank boxes in Missing suddenly seemed very intriguing), but got stuck. Hope you've got further!
One first thought: I suspect that it would make good sense to consider the surviving episodes as well. For instance, Missing lists the 'junking dates' for the missing stories.. but not the surviving stories. But if the surviving stories had been junked, and then copies came back from abroad after they'd been junked, but were saved by Levine and the archives before they could be junked again... you see what I mean, I hope. If nothing else, tracing surviving episodes could provide a clue as to the fate of missing ones. Or at least rule out false leads.
And finally, if you have a solid list of which episodes are suppressed field copies, I'd love to see it. I currently make it Reign of Terror 1,2,3 and one copy of 6, plus all the episodes transmitted from film before 1966 (Daleks 4, Planet of Giants 3, Dalek Invasion of Earth 5, and just possibly Gunfighters 4). But I suspect that might not be a complete list.
Ps: finished. First read, very good. Few maybes, mainly about Ethiopia... But now need sources to dblchk!