with such easy access to the engine, I would strongly recommend testing each one of those MSD spark plug wires for resistance one by one, MSD of today is not the US Made MSD of 20, 30 years ago, my buddy Pontiac Mike had me test my brand new MSD wires reluctantly, and it took three sets to compile one good set of proper resistance spark plug wires
also, please test them in their natural position so on the engine, and not laid out flat on the work bench
"MSD’s 8.5mm Super Conductor Wire will measure about 50-ohms per foot of wire while the Street Fire brand wires have about 500 ohms per foot. As an example, if you have a 4-feet long Super Conductor wire, the resistance should be about 200 ohms. The important thing to check is that the resistance values of your wires should be consistent throughout the entire set. Lengths will vary the values, but they should all be within a similar value."
Coils and Spark Plug Wires Trouble Shooting