I can't express enough how much I love my 80 series. I think a '97 with lockers would be an awesome rig! I came from a built SAS mini-truck and to me the 80 series solved every single issue I had with my old truck, while maintaining most of its off road capability, including needing more interior room, better on road comfort, more power, etc...however...there are a few things to consider with the 80 series.
The gas mileage in the 80 is absolutely horrible. Getting 15-16 highway mpg in a stock rig is about the best mileage one will ever see. Once you add weight, taller tires, the mileage goes down from there. I've actually seen single digits on occasion. I currently average in the low-low teens, although I may be in the need of a tune up and might be able get back up to the mid teens on long highway trips, driving extremely conservitably. I run 33" tires with the stock 4.10 gears and I think this actually slightly helps the fuel economy.
Normally this wouldn't be a big deal, but with gas well north of $3/gal and not knowing where it's going from here, gas mileage could be a concern going forward. For me, my rig is not a daily driver, so the added expense is not as dramatic, but I worry about gas prices go to $4 or $5 in the coming years. I guess in the future, the LC80 could always make an excellent platform for a diesel conversion. But part of what makes the 80 shine so much is the bulletproof 1FZ engine, so I hate to get rid of it.
Another concern is the headgasket. Toyota was forced to stop using asbestos sometime in the late 1980s and during the interum years of the early to mid 1990s, the materials used in the headgaskets were not the greatest. Although some rigs can go their whole lives without needing a new headgasket, it's not uncommon for an 80 series with higher mileage to need a headgasket replacement. Otherwise, the engine and tranny are generally bulletproof for hundreds of thousands of miles.
Size is also a concern, but that entirely depends on the type of off roading and trails you like to run. It is a bigger rig, compared to a mini-truck or Taco. Not lengthwise, but width and hieght. Not sure how it compares to your Jeep though.
I've driven a 2001 Taco and my 1989 Toyota pickup on long trips and both are OK, but can be cramp, and this is where the 80 shines. Lots and lots of room, and extremely comfortable to drive, but can go almost anywhere off road, especially with a mild lift, some taller tires and lockers.
I've only briefly driven a 100 series. My take on it is that is has slightly more power than the 80 even being 500lbs heavier, but has REALLY good brakes, compared to the 80 series. Supposedly the 100 series is bigger, but comparing one side by side with my 80 I couldn't see the difference. I also couldn't see the difference inside. The 100 series felt a little better in terms of highway handling. Didn't drive it off road. I hear the 100 gets slightly better gas mileage, though. With the 100 series having IFS, the 80 series will outdo it off road, but only on the more extreme stuff. However, even on mild trails, the solid axles of the 80 series keep the rig stable and safe and that's where I like it the most.
To me, the 80 series is ultimate compromise between luxery and extreme off road capability, which probably makes it the ultimate expedition rig ever made available to this country. When you look at a few details, you can see that Toyota specificly designed this rig for remote expedition travel, which makes it extremely unique as far as anything else offered in the USA. First you got fail safe double fan belts, then you got a water/debris catch can in the air filter system, then you got a motor that is specificly designed to make gobs of torque at extremely low rpm and is specificly designed to run on low octane pump gas from just about anywhere. The 1FZ motor is just an amazing piece of engineering. It's a motor that is almost exclusively built for durability. Not over powerful, and certainly, not fuel effiecient, but definately bulletproof.
I was shocked to discover all of this as I assumed the 80 series was a creampuff with solid axles. In reality, it's a bush rig through and through, fitting with a leather interior.
Sorry about the long post, I could write all day about it.
I have so more info in the 80 series here.
http://www.brian894x4.com/ExpeditionLandCruiserFZJ80.html
More info on buying an 80 series:
http://www.brian894x4.com/ExpeditionLandCruiserFZJ80FAQ.html
Details on the engine/tranny:
http://www.brian894x4.com/ExpeditionLandCruiserFZJ80engine.html
Slee's excellent buyer's guide on the 80/100 series:
http://www.sleeoffroad.com/newbie/newbie100.htm
Good luck.