True, if the pcv valve is actually free flowing it would be the same as not being there and that would be a huge vacuum leak that could cause a no start. The problem is blowing through may not be an accurate test of the valve unless you have a metered mouth. I think the only way it could free flow would be if the ball inside disappeared or something. Easy enough to plug it off to see if that helps as that would only cause a little rich condition.
Reporting back here with findings and progress after a month of hit and miss, here, there, everywhere. I'm happy to report my little Mustang is purring like a kitten after a top-end rebuild and isolating and repairing the "vacuum" issue. Really appreciate everyone's feedback and hope my type of Mustang doesn't offend anyone; at least she's carrying a stout vintage 302. Here's what I learned.
Matter, it wasn't vacuum related, but rather ignition. One of your posts suggested possibly not vacuum; I'm sure others thought the same. Sure did give me appearance of vacuum problem, deceiving lil girl. Switch was providing 12v to coil at start-up, but 0v at run position. Instant shut down. At any rate, she's happy to be all cleaned up and cuckling at low idle. Still have steering and other misc items before it hits the water. Thanks all. Wilson.