But for $6500 what did you expect. At this point a good condition FJ60 with no rust and everything working and well kept would be in the $25K range. I assume you don't own a welding machine, have never welded, have never done body work. If you did, you wouldn't be asking about the "rusted money pit". We do need to see more images but from what I see so far it looks like a typical 35 year old vehicle but not a parts truck yet and may be worth saving. If you owned a welding machine (and you can learn to mig weld in a day) that repair would be very inexpensive and easy to do. You'll need to do some body work too on the rear quarters and front fender as well as the floors. Look at all this as negotiating leverage if you are up to the repairs. Otherwise walk away. A welder, gas bottle, cart, helmet, gloves, and grinder and other tools will run you about $1000 or more. You need to be a hearty kind of person! Timid people without callouses on their hands won't do well to try and wield a grinder under a truck!
FYI...a suspension kit will run about $2000 and that is with you installing it.
Cruiser Outfitters - http://cruiseroutfitters.com/sus_60series_dakar.html
If you have no mechanical skills you should really be motivated to buy some tools and equipment and learn on this vehicle. It will not be a daily driver until you make it one. So plan on it not being a necessary or primary vehicle. If you need to pay for every repair you should re-think this purchase. Otherwise welcome to the madness.