Spark, plug wire resistance

Are you actually using Taylor wire? Different wire, can be different resistance. "Back in the day" the "go to" universal cut-off figure for factory wires, used to be no more than 1000 ohms per foot, and I don't think I ever found any that high, unless just open.

If possible, photos of a couple of crimps or at least detail how you did that. 600K is too much

You have any wire left? Try jamming your meter probes right into the ends of the wire and take a reading