Only thing i did for wiring on the alternator qas increase the gauge sizes for the ground and charging wire. There are charts online that can show you how thick wires need to be for whatever amps at how many feet.
https://www.google.com/search?q=150+amp ... -cVb5ko0VM
For 150amps. I upgraded the charging wire to 4AWG. 4AWG is plenty for the like 2 feet fron the battery to alternator, i believe stock was like 6 or 8.. you always want oversized for wiring like this coming from the battery/alternator I also upgraded the grounds to equivalent sizes. Remember any positive wire whatever the size you use. You need an equivalent sized ground wire. So if you use 2AWG positive.. use 2AWG negative as well.. this pertains to anything you wire up.
Nothing on the Jeep needs upgraded in wiring sizes. Theyre all sufficient for what the Jeep has. The issue on these Jeeps is there are virtually no relays for things. So the headlights and power windows and so forth have power going to the nain switch directly from the battery.. then th3y go off the switch to the windows... instead of a relay for each window and each windows getting power from the battery through a fuse. Make sense ?
Relays will cut wire length needed to go from 1 switch only from say 10 feet of wiring going three ways to just a few feet instead and directly from the battery itself.. allowing the windows and such to get more voltage. The switch instead should act as a trigger for the relays.. Not as a relay itself
Id ssy the only thing you should be worried about wiring ways on your 90 is just check the condition of the existing wire and replace if needed. Ive found many wires where they were welded together from shorts under th3 drivers carpet/seat. And the insulation shrunk exposing other wires in the engine bay.
Check the orange wires on the harness near the carberator.. and the oil sending unit and so forth. Some wiring on this Jeep isnt fused either.. which can be potentional hazards. Ive found plenty of bubbled.. fused and shrunk wiring on my Jeep. Or chaffed from rubbing things. Check your fuse panel.. make sure you have appropriate sized fuses. One time i was putting my headline back on.. and screwing in the visors cut into the visor wiring.. shorting it out.. qell that small 20ga wire melted all the way from the roof.. to the wires it was bunch up in.. down the pillar. Down to the drivers floor.. all the way to the fuse panel... and that should never have happened.. why did it happen ?? Because some moron put a 30amp fuse in there for the dome lights.. when it should have been somewhere around 5 lol
One of the big ones is the wiring all under the drivers seat. There isa connector there that gets wet wheb these things leak in the rain and it causes all sorts of mess. Mine actually burned itself into the carpet.
Ive also heard of the blower motors causing fires in the dash as well. But when i checked mine the wiring was 10ga wire and looked brand new. 10ga is more than enough for a blow motor. 10ga can handle somewhere around 30amps at 8 feet.. easy