[Hot Rod Reverend]

Why not hook up a hand-held vacuum pump (like the ones used for bleeding brakes) to the hose that is hooked to the carb port? Unhook the hose there and use the vacuum pump to suck air through as a simple test to make sure the PCV valve is oriented in the correct direction to flow air from the crankcase to the carb port.

If you have a set up like Kultulz showed in his post as a suggestion, I do not think that the threaded boss (I think originally meant for carburetor/accelerator bellcrank assemblies) goes through to the crankcase on every single block cast from the factory. As I recall, I have seen blocks that contained holes that that did not go completely through. You may just want to double check that the hole goes completely through in that location.