Being that my engine has only 4 or 5" of vacuum at idle how do I pick a PCV valve for it? The parts store was unable to help me with this question. I don't feel the stock application is doing the job.

Most parts stores have a book you can look the make and model up in. Find the highest factory rated HP V8 you can and try the one recomended for it.

I went through this same issue with my 327, which has about 7" of vacuum at idle. I found that the pcv valve for the 302 Z28 engine is about the best you are going to find to work with a low-vacuum engine. On the bottom of the piston is a stamped letter that identifies the vacuum setting for the pcv valve. Off hand, I don't recall the one used for the Z28 engine. With the low manifold vacuum in your engine, you are probably going to have oil vapor coming out of the fresh air breather on the other valve cover no matter what pcv valve you use, unless that breather is connected to the air cleaner to draw vacuum when the pcv valve isn't as effective at the higher rpm's.

Rod

Your exactly right in the symptoms I've got. I still think I have cam timing problems, but that's another story. Thanks for the information.