Are the wires the same length? The longer the wire the more the resistance. People don't take this into account. (I don't know the exact #s - been a while since I fiddled with plug wires, now you're making me start a new project.)
Go to the auto parts store and tell them exactly what you're doing. They should let you measure the resistance in one (or ideally more) set(s) of wires. Get what you think.
It's good to see you're being so thorough.
I would not like to have higher resistance in my plugs but I would again check vs. baseline (other new plugs, as many as they will let you test). 400 ohms seems fairly high to me for variance on the plugs.
Whatever you do - USE DIELECTRIC GREASE on both ends of the wires.
(Lots of emphasis added here.) That will help regardless.
I don't know if you have tried cleaning the fouled plugs - I would clean them well, then check the resistance again. If it goes down, the extra resistance was due to the plugs being fouled.
Make sure to check the coil too. IIRC there are a couple of tests that need to be done to it.
Remember on the plug wires - check all of them vs. your baseline. Usually on a 4 cyl there are 5 wires - one from the coil, four for the cylinders and they are all of differing lengths. Unfortunately no one has ever come out with a distributor that has all wires exactly the same length. The only improvement over this setup is the one coil per plug computer controlled method, which leaves little for us to tinker with.