I would say that the 280 is sufficient, and the 325 isn't really a huge difference with those dimensions. I think the most important thing is that you scape the tank in a way that allows it to have a lot of space on different levels, etc.
The problem with the brown banded ones is that they get pretty big when they mature (especially if you see them in person). But they
may not get
as big in that size of tank.
I've done a lot of research because one day I really want a catshark tank/indoor pond.
Depending on if it is a male or female and what is maxes out at you can always rehome it. Which will be tough, but you can be selective and if the home is really good and the person isn't an idiot and can care for it then you'll be happy knowing it'll go to a good home, and you can try another shark such as a coral cat or marbled cat from an egg which stay smaller.
I hesitate on the ray. I love Blue spotted rays, but they get pretty big, and I feel like you want some rock work for the shark to travel through, and that might interfere with the ray and it's happiness (cuz they get BIG) I was shocked how big they get in aquariums.
But I would hold off on the ray, and the shark should be fine.
If you give it love and care you should be good. Often those sharks cannot even get out of the egg on their own, and you are giving it a chance to live, and not have to worry about predators.
Lmk if you have more questions. You can also personal message me. I did sooo much research. Too much probably since one day I really want a catshark. I absolutely love them
(You could also consider an indoor 300 G rubbermaid pond, but not sure if the look appeals to you).