Intake manifold Not seating properly (?)

The bad reputation of the cork gaskets was caused by another component. They worked fine from the factory, until the pcv system got clogged. Crackcase pressure is what pushes them out. the fact that they are nearly cut in two by the dowl pin hole is a contributing factor. ( The same "PCV caused a failed Gasket" condition was at outer rear corner of GMs right valve cover ). Anyway... I do throw the cork away, remove the dowl pins, clean those pin holes and fill them with RTV as I build a RTV gasket. This makes the RTV stronger ( better fastened ) in this one location. The only thing even better we could do is mill a groove in intake or block to secure the RTV. See Honda or other T shaped profile vulcanized rubber gaskets for example. Bottom line.. If the PCV system isn't maintained, that pressure is going to escape somewhere.