That's a big gap, but it is possible.
If you have the PHS documents for your Judge, you will find the Engine Unit Number on the shipping broadcast. In addition to the VIN stamp, your engine block should be stamped with the last 4 digits of the engine unit number in the vicinity of the two-letter code stamp.
If the engine unit number matches the PHS documents, it certainly would appear that you have the original block.
As far as the intake manifold question; a May casting date is quite early for the new model year, but all the sources indicate that the 9799068 manifold was a 1970 part. Not sure what to think about that one...