You can use pretty much any PCV valve, unless you have a really low vac signal. In that case, try one from a 1970 Corvette LT1 350 (last of the solid lifter HP engines). Otherwise, try one for a 250 Chevy six.
When mounting a PCV, try to put it where it doesn't have oil splashing directly on it, or you will be sucking in more than just vapors. Mounting it in place of the road draft tube is usually a safe bet as it is usually baffled.
One last thing, when running a PCV valve, you can't have a sealed engine. You need to have either a breather located somewhere on the engine, or a vent tube running from somewhere on the engine to the air cleaner. If you don't do one of these things, you will be pulling a hard vac on the motor which could cause the gaskets to leak or possibly worse.
