I won. But the victory was bittersweet, because #OnlyNasThings, and around the 08:05 mark Transmogrification and Retsu just happened to coincide, resulting in insta-death. I really fought with myself on finishing, obviously because of the resulting time advantage. But, 8 remaining minutes would have been an enormous window to take one down from 35%. I felt like I earned it anyhow, so many times I lost to the clock, and that stupid CS.
So yeah, if you're going to attempt this, you need BLM/WHM and NIN/WAR. You'll need INT & MND sets for BLM, as well as Evasion and Nuke sets for NIN. Don't worry too much about Accuracy, they're only Tough mobs with a ton of HP. Evasion and debuffs are the only thing that's going to see you through Sword form. Those are Horomusha's, but you shouldn't be tanking in Ochiudo's anyway.
https://youtu.be/1_x9taHxxgs