I've started a GitHub repo specifically for a possible emergency PoW change hardfork.

https://github.com/BitcoinHardfork/bitcoin

While I understand this thread works under the assumption that a PoW change will be done unconditionally, and this code can possibly be used for such a purpose, please note that it is being developed it from a strictly emergency-use-only standpoint, since the community has not rallied around the PoW change idea at this time.

I would appreciate any review and/or contributions others can provide.

The repository does not intend to select an algorithm until such time as a PoW change is needed.
For this reason, the code is being designed such that the algorithm is configurable.
Therefore, please feel free to contribute new PoW algorithm options.