Did the original die? If so, you might look online for a replacement housing or a dead GPU that you can steal the cooler from. Those are your best bets for a compatible replacement. You can find those on Ebay. You could also create and WTB listing on craiglists. Maybe draw out someone who has a dead card lying around that didn't consider selling the HSF.
Otherwise, there are some AIO adapters that might work. I think Silverstone used to make a GPU heat sink that supported a pair of 120s. IIRC the heat pipes came out from the top side, right where those two ram chips are, which would be bad as you wouldn't be able to put heat sinks on those two chips.