In every case you need to care about the forum rules, which are, that you need to care about the right topic and an info-header. See https://forums.factorio.com/forum/vie ... f=89&t=947
If not chance is high, that your mod will be rejected.

Then you have two options:
1. Just create a new thread in the right board, just like anybody else. Then report your pre-alpha-thread to be locked/forwarded to the new.
2. You can move the thread, see here: https://forums.factorio.com/forum/vie ... 89&t=13987
(*) For the work-in-progress mods we turn a blind eye on. Sometimes it's good to just spread your idea without having to care about conventions.