Exactly. A V8 swap is arguably simpler into a ‘91. Having owned both, I'd prefer a V8 to a 1FZ. Have a look at the classified ads on ‘mud as well. You may find an 80 built the way you want there.
My other two cars are 1969 and 1932, so I'm used to old and unrefined. And I have owned a first gen 4Runner. The lack of power isn't a concern for me...my previous Jeep was a 2011 with the 3.8, and everyone knows what a dog those are.
I've been pouring over Mud for the last few days learning all I can. Trying to get the Jeep ready to sell sometime next week, then I will see if either of those two LC's are still available, or what else is on the market at that time.
You'll love the 80 series...fantastic all around rig. There's a supercharged locked 80 in the classifieds on Mud. 14K and a TON of maintenance including fresh engine rebuild and new SC. Located in Boise...won't last forever.
Oddly, I can be helpful here... I went from a 2013 2 door JK to a '92 FJ80 late last year. I wanted more space and didn't feel like spending the insane money for a JKU.
I did know about the significant differences between 91-92s and 93+ 80 Series, but I found a 92 for a good price with low mileage that had everything I wanted--lockers, sliders, winch, etc. Is in great shape and had been well taken-care of by previous owners. That helped, as a lot of the baseline work had already been done. That said, I've put some money and elbow grease into it in my short period of ownership thus far.
My thoughts: this is a big, roomy, and heavy truck. I like the space because I camp a lot and have 2 big dogs who took up the entire 'trunk' of my JK. It's a satisfying vehicle to drive and in some ways, rides better than my JK. That said, it's not a modern vehicle. No airbags, no ABS, and terrible gas mileage. I averaged 12-14 mpg on my 1500 mile trip to drive the truck home, and now get about 8-9 mpg in the dead of winter on short drives around town. That hurts, even coming from a JK on 35s that got 13mpg around town. Even so, I'd have to drive a hell of a lot to spend more than I had been spending before on my Jeep payments when I had them.
Power is lacking. I can't speak for the FZE, but the 3FE is basically a fast tractor. (At least it's faster than my land Rover.) It has loads of torque, which is great off road, but you'll feel the power shortage on long uphill climbs on the highway. The truck goes 0-60 eventually, even if you floor it. I drove my JK like a sports car. My wife has a newer V6 Cherokee and the thing feels like a Lamborghini compared to the FJ80. But, I'm more of a slow 4x4 kind of guy. The FJ80 kills it in the snow. Again, it's a big, heavy truck.
Long story short, the two are very different trucks, and I'll echo everyone who said that you need to remember you're going back 20+ years in time to get into an 80 Series. Make sure you're handy and don't mind turning a wrench. These trucks will last forever if you're good about PM and don't neglect little problems. I've been pretty happy with mine despite all the differences. If you're looking for a go-anywhere truck that will still be running after the nuclear apocalypse, a Land Cruiser is for you. But if you're looking for something with as many features and creature comforts as your JK that gets great gas mileage, expect to be let down.
So I went ahead and pulled the trigger on the 91. Of the couple I found in my area that were priced around what I was looking to spend, it appeared to be the best cared for. No peeling or faded paint, and the interior is pretty good shape (8.5 out of 10). Still had the original owner's manual with the cover from the original dealer in the glove box. It's old and it's slow, but so am I, so it's all good.