I’d give up the Gunfighters because the story is just… kind of lame, really, and exchange it for The Daleks’ Master Plan, it’s a great serial filled with action and sets which would benefit from being on video.
How recent can I exchange?
I would want to get the missing episodes of Marco Polo back. It’s a really good serial and would be cool to see the sets and costumes more clearly.
Can I exchange Love & Monsters? Honestly I would destroy that story even if I got nothing in return.
The Daleks’ Masterplan is an obvious candidate for a missing story, but I think I’d also be happy to swap Planet of Giants for Marco Polo.
Alternatively, I’d swap the two surviving episodes of The Crusade for the missing two episodes of The Reign of Terror. The Crusade doesn’t really work for me, as it is unlike most other 60s historicals where there is a clear historical arc (e.g. buildup to the burning of Rome in The Romans or the fall of Robespierre in The Reign of Terror).
Can I just get rid of all Dalek episodes from this point on? Pretty please with a Cyber War on top?
I would trade all of 12 and 13 for all of 1 and 2. :)