Okay so, as per discussions, I'm no longer going to maintain these, or give them official status, going forward.
I will leave these versions available to download until such time as there's a generally-accepted community replacement (or, that I feel enough time has passed that the lack of such a replacement indicates there isn't enough demand to warrant it). Anyone wanting to do this is welcome to use these versions as their starting point if they wish.
To avoid confusion between different replacements, please make sure that any are named in a way that clearly indicates their nature. For example, "Bob's Lemmings Conversion", not just "Original Lemmings". This means that eg. in the context of challenges etc, people can clearly talk about "Bob's Lemmings Conversion", rather than just vaguely referring to "a conversion".