I picked up an E-coil from a salvage yard for something around $5.
With that said, for the 258, the stock canister coil (round one), is just fine.
IMO you don't gain enough to justify the cost.
As far as ignition modules, go to the salvage yard and pick one up. Doesn't matter if it works or not. Purchase the GM module for around $24 new. Gut the insides out of the salvage module, keeping the connectors. Hook up the GM module to the wires, and keep it as a spare. Run the one currently in the Jeep until, if ever, it fails. Then just plug in the new one. Do a search on Stealth GM ignition module to get the wiring diagram and instructions on how to do it.
So money is really not the issue, and you will get the most out of your 258.
79 CJ7 "CJ Express" 4.2L, NV4500, D44 rear
69 800 with SBC, SM465, NP205, 14BT