well, you can start by checking out the overclocked
cpu database right here at AT (you can use it to see how high everyone else can overclock their 1.4's)
I'd suggest a thermalright sk-6 with a fast delta fan , OR, if noise is a problem, a nice quiet 80mm sunon fan mounted diagonally on it.
if you want some reviews , check out the AT
socket A cooler roundup from september