Factory Correct 1964 PCV Valve

Quite a few years ago, I purchased a metal factory correct PCV valve for my 1964 Slant 6. I believe I purchased this from Goodmark. I no longer see them listed on their website. How often should I replace the metal PCV valve? I did find some on the following website, but the price is much higher now.

Chrysler, Plymouth Dodge, Desoto Pressure Control Valve, PCV