You're avoiding the question. What would it take to convince you?
Genetic evidence that it occured. Geological evidence that it occured. Biogeographical evidence that it occured. Forensic evidence that it occured. Paleontological evidence that it occured. Archeological evidence that it occured. Cosmological evidence that it occured.
In addition to all that, there would have to be a
lack of evidence that it did
not occur; in other words, we should not be able to make observations that would be impossible to make if the Flood had actually happened.
That's what it would take. I know it sounds like a lot, but what you're talking about would be the most important event in the history of the world if it were true. That demands a pretty high standard of evidence.
Unfortunately what we have right now is no evidence, from any field, that it did occur; and an enormous amount of observations that would be impossible if the Flood had actually happened. In other words, we have no evidence
for and significant disconfirming evidence
against.
It's a shame that a reasonable discussion and exchange of ideas cannot be conducted without slamming the door on alternate theories, etc, due to the fact that the only "accepted" theories must be purely naturalistic.
It's not that we'll only accept naturalistic theories, its that we'll only accept theories that are not contradicted by the evidence. The Flood, unfortunately, does not meet that standard.