I have just gone through the same experience as in this thread - motor coughs twice at 3000 rpm and stops, rotor doesn't rotate properly when motor is driven by starter, pull distributor and the pin in distributor drive is broken... All this happened after approx 2 months of Pantera ownership and with no previous experience of American V8s - gee was I worried when the motor went out! After the Pantera's first trip on the back of a truck back home, I have searched these forums like a man possessed and from the info found here have now managed to diagnose the problem, pull the distributor and replace the drive pin and assemble it all, and get it to start on the first twist of the key - thanks to all for your great info
I have followed George's method of setting the timing - set it all up at approx where you think TDC is then twist the distributor clockwise until the idle is at the fastest - however in my case the engine hesitates quite a bit and bucks a bit when accelerating under these conditions, clearly not happy, so I have needed to back off somewhat, resulting in a markedly slower idle which lopes (it did this before the drive pin broke so I guess this is pretty much how the timing was before). Perhaps the slow and loping idle is a sign of other issues, and maybe the carbie (Holley) needs a good sorting. I have no idea what is in my engine - there was very little info from the previous owner(s) but I believe it has a '3/4 race cam' - but that could mean anything (no idea from which manufacturer), and I have no idea of any other mods except what I can see: Aftermarket air cleaner, the Holley carbie, an Eddelbrock intake manifold, big bore headers and Duraspark ignition.
Cheers, Tim.