:?The machine shop botched the job and tried to fit the block with a cast crank (and different bearings). The engine bore technician told me last week there was some problem with fitting the bearings (which had to be reordered), .

Hmmmm.....the plot thickens more. Good article on the /6's - thanks for the tip and timely info, Josh. By the engine stamp # on the block, then, it appears quite likely it is the original motor for the '73 car. I see 2 possibilities explaining the dilemma: 1) Either the guy who sold me the car rebuilt the motor (or else had it rebuilt) incorrectly with a cast crank, or 2) The machine shop botched the job and tried to fit the block with a cast crank (and different bearings). The engine bore technician told me last week there was some problem with fitting the bearings (which had to be reordered), so I'm betting on #2 but I'll hear what the shop owner has to say tomorrow. In either case, though, I don't think I should accept the work. If there were issues/ problems/ questions encountered during the job, he either should have done a little homework and/ or let me know what was going on before he went ahead and did any "creative engineering." The fact that he was "incommunicado" lends me to think something went seriously wrong here. I'll keep you posted regarding the outcome.