[Mr70]

How does the blocks VIN characters match up against the VIN stamped on the Turbo 400?
I would get within a nose length of that VIN stamping down by the oil filter if I was you,and look at it very carefully,as well as the NO VIN void on the pad behind the alternator.What do the broach marks look like there?,and especially with that head removed.
If authentic,the blocks casting date,although unusually early,is not entirely impossible for a baltimore build for April..I have seen 3 LS'6 with a December block casting,assembled in March.Some of those bare blocks did actually sit around longer then others,before being assembled.
I've not seen unmolested engines with head dates that far spread..I would lean that one of em was replaced much later on after the initial assembly.
How does the VIN match up against the cowl tag sequence number?
What does the Turbo 400's assembly date,serial # and it's CY tag look like?..because they are repoping those tags.
What is the rearends casting date/assembly date & ratio?