Do you have a mag base and dial indicator there?
You can check lift at the valve compared to the others...this would tell you 100% for sure if a lobe is gone.
Otherwise, I would go ahead and pull the intake and take a look around.
Make sure when the engine comes out that you check some bearings. If a lobe is gone, that much metal pumping through an engine will wreak havoc on the
oil pump/bearings.
You're in good hands with Barry...and this only goes to show that a cam can go out even with an experienced engine builder. And it shows why I don't use flat tappet cams.
