The plug wire does INDEED unscrew from the ignition coil:
So I replaced the wire with a performance one I had left from my truck:
Filled the cap with black automotive silicone sealant before I pushed it on.
Had to find a thread-on cap for my sparkplug, which can be a problem as a lot of them are molded right on the plugs now:
Done...still doesn't run properly though:
