After a bit of googling, it looks like maybe the 6610 2 post ears would work on the 6450. Problem that I see is that the 6610 ears are longer by 2/3's than those for the 6450 and would cover the side vent (6610's have the vent up front on the side right next to the ports). I could measure/take pictures but I'm guessing that even if they do fit you'd want to cut them down to prevent them from covering up the vent.
This listing has a side shot of the 6610 with rack ear on it: 6610 ears
On a side note, I could apparently sell the 2 post ear kits for the 6610's I have for a small fortune as no one seems to have them anywhere for less than $70+ shipping. Brand new in the wrap still. lol