I have three strict rules I follow on spark plugs, to wit:
NO Champions, NO NGKs, and NO copper anything.
Or else :hang:
Speaking not particularly about Jeeps but just in general, I have had too many bad experiences with copper core plugs used as anything other than fishing sinkers.

I have Champion, Autolite, AC and NGK V-Power copper core plugs in my tackle box and would never put another one anywhere near an engine, I hate them that much. YMMV and they might do okay on a Heep where they would reside on the cold side of the engine but I personally wouldn't risk it.
Steel core and air gap type plugs are obsolete because they are no good for anything that doesn't have points, which leaves us with...
Platinum. :thumbup: After struggling with the various copper plugs as recommended by GM for my old first generation S-10 truck, an angel came from heaven and introduced me to Bosch platinum plugs. I took a look at the teensy little ceramic shrouded electrode and laughed but the angel said to me "what have you to lose but twelve bucks and fifteen minutes" so I said what the heck. I put 50K each on two sets in the old S-truck before I sold it and I have to say that's not too shabby in a rig with a recommended 12K tuneup interval where I was lucky before to get by without putting in a new set between oil changes. Used Bosch platinums in two other cars also with no regrets.
Now my Heep had Autolite platinums in it when I bought it. I don't know how many miles are on them but I checked them when I changed plug wires a couple months ago and they all looked good except the one that was running under the bad wire so I changed just the one with another Autolite and it seems to be just fine. I won't be afraid to try the Boschs when it's time though.
Oh - Bosch offers a pretty decent set of wires, I can't remember what the name is they have on them. A bit spendy, I think I paid 25 clams for a set, but just the right length and lifetime guaranteed (yeah like we save our receipts).