It'll fit, no fan though unless you find a REALLY thin one. A bigger heatsink should take care of it though, I made one out of two smaller heatsinks when I had a 3640 in a 3000D. The 3640 I had came with a heatsink that was too tall anyway, so I ended up having to go shorter and wider.
edit: or a blower fan alongside the heatsink could probably work...