Which HD5850 for O/C

[Hi_Clocks]

Hey guys, Im going to be building a new watercooled rig and need advise on which HD5850 to get that can overclock well? I have heard some say MSI cards are the best and ASUS but I am unsure of which one to get?

Budget is less then $330 shipped.

Also, I am looking at cooling it with the EK HD5850 full coverage waterblock
http://www.frozencpu.com/products/99...kel.html#blank

So I want to be sure this block will work with whichever card I get, as Im new to watercooling.
Thanks for your time.