I have a fuel injected 8BA with a pcv system and still get the same smell in the cabin, with some of the same effects you mention (complaining wife!) but no headaches that I have noticed. Putting a pair of Flowmaster catalytic converters on killed the smell but they only lasted a few thousand miles before they were overwhelmed by the flathead! The idle AFR has to be fairly rich in a flathead for a smooth idle due to the combustion chamber design, I think, and some unburnt hydrocarbon smell is inevitable. Ken