I'm just going to throw this out there as something to consider. I can tell by what you've already accomplished that you have no reservations to getting your hands dirty.
I question how "oily" the cats can be. Let's think about the sequence of events and how oil came to be in the cats in the first place.
Flood waters rise and enter the muffler. water fills the entire exhaust system and enters a couple cylinders, (intake valves are at top), then displaces oil to the TOP of the crankcase and back out through the cylinders. Because the exhaust system is entirely full and due to phase separation (oil floating on top of the water) then the only contact of oil to the cats is at the top of the substrate as the oil migrates out the exhaust in a thin stream at the surface of the water. What does this mean? It is likely there was only a minor stream of oil in the exhaust at any given time, far less than the flood that would be seen from a failed AOS that experienced hydrolock. The water/oil did not form an emulsion since it was never sheared. Certainly cleaning is not going to hurt anything but is it necessary?
Regardless I am enjoying this thread. Keep up the good work!
The point of this post is: in my experience with flooded boat engines is that the quicker you could get one running (usually hours) the better. Detailing can happen later.