<VV> Starter Mystery

[Brian]

I'm stumped!  Here's the story.  The car is a 1968 110 PG.  Three weeks ago while the owner was going 65-70 MPH on the interstate, he began to hear a loud knocking sound from the engine.  within a mile the engine had seized.  He pulled to the side and turned off the ignition.  He then turned the key to the run position.  For just a moment, the warning lights came on but hen the entire electrical system was out.  No lights, nothing. The battery ground cable and some other wires were HOT!
The car was flat bedded home.  About two hours later, the electrical system again functioned.  Needless to say the engine was locked solid.  A tear down showed number 6 rod bearing welded to the crank.  A total rebuild followed.
Before installing the engine, the oil system was primed and checked with a guage,  It had more than 45 PSI at about 800-00 RPM using  a big electric drill.  The engine turned freely and smoothly by hand.
After installation, the engine was static timed.  When the starter was used the engine turned over slowly as if the battery was weak. The mystery began when the key was turned off and removed.  The starter continued to slowly turn the engine. Two starter, a new ignition  switch and a new neutral safety switch failed to cure the problem.  As the starter turns after the key is removed the battery negative cable get HOT!
All types of tricks have been tried.  Disconnecting, the alternator among other.  Nothing stops the starter from turning.  The car has a new engine compartment and body wiring harness. It also has a new stater 'mini-harness'.  The car has a Pertronix ignition.
I'm stumped.  Any ideas? Thanks in advance.
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