Is it allowed?

Only one way to find out, admittedly I didn't know Overblood had a PSN port

Very true just gotta do a run and see if it gets accepted.

Oh yeah it's on the Japanese PSN store only

As there is no verification requirements for this leaderboard. It can not be rejected haha.

I am not aware of this particular version tbh, or if there are any major differences between them all.

If it's really broken compared to the other versions, separation of boards could be an option. Or just accept it's the fastest version, and stick with 1 board.

Currently there is no OverBlood speedrun community/discord of some kind that I'm aware off, where we can discuss these kind of things rules/moderation. So it's all my own perspective.

Goodluck on your runs!