i do have an h100i i will likely get a fan controller for those fans for now they're running off of my 5 volt line and i'm working on getting a fanless psu.
I wouldnt recommend trying to passively cool a mid - high end card. It's only going to end in disaster. No matter how you look at it you will need to remove the heat away from the heatsink. Even those 7850's that came out a few months back that are passively cooled dont take long to overheat and cake em selves without really good case ventilation.
If you are dead set keen on being as quiet as possible stick a waterblock on the 660 and construct a proper watercooling loop with low rpm fans at 5v.
Also there are acoustic foam panels you can get for your case if that interests you. Or even sound deadening material used in cars. Both work really well but can be a little pricey.
unfortunately i doubt it, the pcb layout would be different. but if you look hard enough you im sure you will find something of the same scale. quitepc.com would be a good place to look if they don't have anything like it in stock, i would reccomend contacting them and asking if they can find anything like it. considering passive cooling is something they are big on. saying that have you seen there passive cpu coolers they are huge!