The dent in the pan interfering with the crank was my 1^st. thought also.  But the previous owner says the dent was not that bad.  It interfered with the oil pump feed pipe but didn’t go beyond that.  I haven’t ruled out the flywheel, clutch or pilot bearing yet.  The hunt continues J

Vibration update.  I went through the ignition, plugs, plug wires, cap, rotor and HEI module.  The plugs wires were in bad shape and I had 2 spark plugs that seemed a little oil fowled compared to the rest.  This took care of the vibration the started around 3000 rpm.  It’s very smooth now at highway speeds.  I still have a minor vibration that starts at 2000 RPM and goes away at 2500 RPM.  I think its flywheel or clutch related because if does it with the car parked.  The hunt continues.

After more driving.  I believe it's definitely the clutch/pilot bearing.  Here’s why I think this.  When I get above 70MPH, the shifter vibrates is like the business end of a jack hammer.  If I press and release the clutch, the vibration changes.  Sometimes when I press and release the clutch, the vibration goes away all together and its smooth as silk up to 90MPH.  I would think that would rule out the universal joints.  Do you think I’m on to something?