No apology needed, I never read your post as inflammatory. As I said I've never run a 292, have run a 280, but like you I would expect a low vacuum reading. I'm not sure that the vacuum advance would help although it may work with the Rhoads lifters and connected to manifold vacuum. Sometimes these things are worth a try, especially when it just means switching a hose around. I would also be looking at the complete timing curve/initial/maximum etc and making a note of exactly what was set to where.
I think the problem is that we are all trying to help here but it's hard enough when the cars in front of you let alone over the 'net!