this is shaping up perfectly. and pre-50 years ago it was probably inevitable that there were a few security/technological leaks thanks to an opportunistic person or two, so there's room for the seekers to have a notion of what the island nation was like (and then the fact that it went from isolationist to completely silent was probably a politically noteworthy point). i imagine the way the folks who left feel is that... better to swap precious things for secrets and forbidden knowledge than to risk losing everything so at the very least one of them would be very on board with the trade
i love them both and it's such a struggle to choose. other dream pbs i want to see for the period aesthetic reasons: harry lloyd circa manhattan, and while i'm at it, ben whishaw and romola garai too