A big thank you for enquiring on my behalf!
A 503 would still require a GAE instance to be running so wouldn't necessarily deal with my problem.
I have seen "noindex nofollow" kill a site stone dead in the past so I am very wary indeed of using it. In my experience once you've noindexed a page it is nigh-on impossible to get the engine to index it again.
My content is autogenerated, though I hope it has enough value to be considered useful. It's time-series data of word frequencies in politics, so for example you might use it to see how one candidate is doing relative to another in an election campaign.