Single Slot (full size in a riser) GPU

Greetings All. I am in the process of turning a DL380 G6 into a personal game machine. Because its a 2U chassis, space is VERY limited. However, I can use a riser to put in a single slot card. The problem - its EXTREMELY tight - the card has to be a TRUE single slot by every definition. No heatsink sticking out farther than the faceplace.

Now, if your knows this box, it has MASSIVE air flow by design. So I could conceivably replace the stock cooler with a true copper "thin" one - but I would rather not have to do so.

Thus - what is the best available, true single slot card out there?

Power consumption is not an issue - I can go up to 225W which covers about anything. I know I could use one of the dinky 430's but I am running dual xeons with 48G - I can hear the card squealing in fright already. I have seen a couple of discontinued 4670's on newegg/tigerdirect - but can't find any truly high end cards that will fit the need. Is the riser going to limit me so much as to not make this possible?

What card - if money were not an issue - would you choose for this solution?
*Note - this doesn't mean changing chassis, or doing any chassis mods. The solution must be an "off the shelf", commercially available product.

Thanks!

CH