Pitting would not cause overheating. Chances are it's something else. If it's only getting hot at idle, a few possibilities come to mind--a failing fan clutch, calcification in your radiator, or too wide of a clearance between the pump veins and the divider plate. What is your ignition timing set up? If you're running vacuum advance off of ported vacuum then your engine will run hotter at idle compared to running it off of manifold vacuum. An original '67 setup would run off manifold vacuum, which kicks up the timing to about 26* advance at idle. Ported would keep the advance at 6* BTDC (if that's where you set the initial timing).
Go to the heating and cooling section of PY and read the first thread. It has GREAT information on making your water pump as efficient as it can be.
http://forums.maxperformanceinc.com/...d.php?t=411256