I built a coat/broom closet between the dining room and living room, and it needs, well, closure. I built it into unused space on the end of the pop-out that covers the steps down to the basement. I decided not to hang an ordinary interior door, as it would face the living room and look like a door to the basement (which actually is on the other end of the pop-out and not visible from the kitchen, DR or LR.
Here's a view from the LR -- the bookshelf will take the place of the folding photo screen, covering the closet behind it:

and here, a side view of the popout. At the right end is the door to the basement; on the left end will be the new, hinged, unit:

So, all along, I have planned to construct a bookshelf that would swing out on a hinge, the outer -- opening -- end supported by a rubber-wheeled caster. Just pull out one side of the shelf unit, and there is the closet.
I am about to start construction of the shelf unit, and am looking for some 'hing-ineering' help: Three or more strap hinges, or one long piano hinge?
Has anyone here ever hinged something like this? The unit, at about 44" W x 84"H and roughly 12" Deep, will be fairly heavy -- 3/4" cabinet-grade plywood and knotty alder trim -- hence the support roller on the swinging end.
But, I am not sure where to find a piano-type hinge that would work, considering the size and weight.
Any thoughts and suggestions would be appreciated!