When you select a case for your next build, look for a positive pressure case with washable front air filters.
In such a case, all air is drawn in through the filtered front fans so dust does not enter.
A example that I use is the Silverstone TJ-08E, a M-ATX case that sells for $100 or so.
I rarely need to clean the filter, perhaps every 3 months, and never the inside.
An example of a full atx case that has filters on the front input fans would be the Antec 300.
I like the direct exhaust cooler of the GTX670 you linked. It gets heat directly out of the case.
The GTX670 is not a hot card to begin with. If you want to overclock the card, fine. But if you are adding a cooler, to do so, I think it is smarter to spend the money on a factory overclocked card or a GTX680 in the first place.