There are also 4 ram chips on the back, but that doesn't matter really.
I would think the challenge would be fitting a fan somewhere in there...
Would it be possible for you to make something that can hold the fan from the stock 4850 cooler, like in the pic i posted above (posting here again so you don't have to scroll back up

)
I was thinking of trying to get a hold of a stock 4850 cooler and taking the fan out, have you make a custom heatsink, and maybe a custom shroud.