So all went as planned with the engine and transmission rebuild with one notable exception.  After running it for 30 minutes and shutting it down to re-torque a few things a dime sized oil spot was on the ground.  After raising the lift for a closer look it was clearly weeping from the torque converter cover hole - oops!  That looked a lot like it could be a rear main seal leak - one of the very leaks that we vowed to rid this motor of.  So with much more looking and feeling it was found that the crank snout was dry, but the oil was unmistakable.  So this meant either the pan gasket or a rear oil gallery plug or the cam bearing plug was the likely culprit.  In either event that meant one thing - the motor had to come back out.  This is what "extra work" looks like...

While there was no rushing going on when re-assembling the engine, obviously something was not quite right.  So painfully this added a days work to pull the motor back out to fix what should have been right from the beginning - ouch.  Sure enough the problem was pretty obvious when the flexplate was removed.  There are 3 oil gallery plugs as well as the cam bearing plug on the back of a Big Block Chevy.  All plugs had the proper sealer on them, but the large one above the oil filter boss wasn't tightened enough.  The threads are NPT and you really have to run them in good to assure proper sealing.  It was obvious that I didn't get that one tight enough and cost myself a day due to it.  So it was removed, cleaned and resealed and TIGHTENED before the motor went back in.  As they say, we all make mistakes and for the record this was my first and will be my last...

Here the plug has been removed (below the left freeze plug)