I am also suspecting your throttle blades are too far open at idle exposing the transfer slots. The Holley 390 has some pretty small primaries. Even a "little" 318 will draw more at idle than a 390 will be set for out of the box. Remember that they are generally used on 2.5 to 4.0 liter engines. If there is ANY vacuum at all at the timed port (right side of the metering block, where the vacuum advance connects), this confirms. Easy to fix on a Holley, there's a secondary stop screw. Try about half a turn clockwise.
Also according to the cam card you show, your cam has 112 centerlines with 4 degrees of advance "ground in." Advancing another 3 degrees may have been too much of a good thing.
A great place to start for a PCV valve would be a common Mopar style valve of something common like maybe an 83 318. They were pretty much the same.
Was this originally a 2 Bbl or 4 Bbl engine? The mid 80's 318 4 Bbl engines had an insanely low compression ratio. Like 7.5, which is low even by 318 standards.
