I'd prefer keeping the story in the Harry Potter universe, though I agree with your second suggestion about a more stable Tom Riddle.
That was my initial plan.
I tried to answer you yesterday, but webnovel wasn't complying...
The truth is I was stuck in my writing and a conversation I had with my girlfriend about flying sharks, of all things, came to mind, and I decided to roll with it.
She was quite happy when I told her that I included the topic in the fic.