My personal opinion. Dont do it. Completely recreate it from scratch, and dont even base some stuff in your own blueprints on it. Then its ok. Everything else is at least morally bad; If the original pack was bad and not working, well, thats cra*, but it doesnt give you the right then to sell an “optimized” version based on the same setup.
What i dont really understand is, why are you even asking here? I mean, you ask if people think its ok, people say no, and you go like “i will submit it anyway” and “trolls” etc. Did you just look for some absolution from the community for your submission and are now mad because you didnt get it?
Edit:
“Similar with large changes” / “fixed version” != recreated. Recreated means, you did it from scratch which you clearly did not, as you yourself stated multiple times in your post.
And indeed, code counts as intellectual property too from a legal perspective. Granted, its not yet completely clear where the line is, but ask Oracle and Google about this topic.