SM Head Install... forgetting anything?
Not sure why you guys are suggesting the gasket is upside down. The shiny surface below his valve cover is the machined finish on the cylinder head, not the gasket. Plus, how can a SB exhaust gasket even be installed upside down? The bolts holes on the outer ports are offset.
Is there anyone here who's made a warped set of old headers seal with stock exhaust manifold gaskets? That's his problem.
@DentalDart - It's time to invest in a decent set of gaskets. Percy's of Remflex gaskets will seal your non-flat flanged headers. Alternatively, you could always try some heat heat red rtv. I know a couple racers who only use rtv. Just let it setup for a day before firing it up.