Need a little help with this. I am wanting to do this pose with a similar base but instead of a wall habitat I am wanting to have a floor base that will sit on a shelf that goes over a entryway hallway and looks into the living area. Any ideas on what based I would need?

I would suggest making your own base.That way, you can make it exactly how you want it to be.

Make the shelf be an artificial rock and put the cat on top of it over the door.

That looks good Rob. I'd love to see the full display.