I would go with the opteron 165 if since you are planing to oc it. With a good mobo you will get about the same oc with either one. The opteron 165 has 512kb more of L2 cache per core.
I have a Opteron 165 and love it. Right now I have it at 2.2ghz@1.375volts stable. Mine will do 2.4ghz@1.425 stable and 2.5ghz@1.525 stable.
But your mileage may vary for beter or for worse.