The pics beg the question: Did the front and rear manifold gaskets blow outwards or did they move/get sucked inwards? The crankcase is, for purposes of this discussion, a sealed system and includes not only the crankcase, per se, but all areas where oil flows and returns to the pan, IE, oil pan, valve covers, galley under the intake, timing cover, etc. The job of the PCV valve and hose that is plumbed to your carb is to provide suction/vacuum to the crankcase system to relieve and evacuate pressure in the crankcase from blow by (even the freshest, tightest engine will have at least a little blow by) evaporating oil, etc. The filler cap on your driver side valve cover needs to be a filtered vent to allow clean fresh air into the crankcase to replace the air sucked out by the PCV. Picture what happens when you suck on a straw and then put your finger over the open end. If you suck hard enough the straw will collapse. The unvented cap is basically your finger over the end of the straw. All that said, I agree that properly applied beads of black RTV are a vast improvement over those damned end gaskets, however, your PCV system needs to be addressed also.
HTH,
Gene