You have a few choices on how to lift. The best way I reccomend from personal experience is to get some Old Man Emu (OME) rear leaf springs, I would suggest the 2" lift version. These springs are super flexy, very comfortable, built extremely well and only cost me $100 each. You will also need bushings, possibly front pin hangers (from dealership) as they could be corroded/welded together. I also went with the OME greasable shackle which gave me yet another 1/2" height increase. Also you will probably want to get some new U bolts. I picked up the Rancho U bolts for Toyotas and they are great, cheaper than the OME U bolts. And finally, you are going to need longer shocks, there are several good brands that are made for 2" lift applications. I grabbed a set fo KYB MonoMax (from partsgeek) and so far they are pretty good. They aren't Bilsteins or OME but they are good enough for the daily driver/mild off roader use.
Again, for the front you have a couple of choices. You can get an IFS lift kit which looks like a PITA. Or you can get beefier torsion bars that you can supposedly crank on without preloading them too much so that you don't sacrifice ride quality. And then there are ball joint spacers. I just installed a set of BJ spacers on my 1987 this weekend. I don't have much to say about these yet as I slapped them on, took a quick drive then parked it to start an engine rebuild on my friends 20R. I can tell right off that it has a bit more travel and I can hit bumps much harder and notice more flex instead of the soft bottoming that it had before the install. But without an alignment I didn't feel like driving it around too much. The ball joint spacers are 1.5" high and will give you 1.5" of lift. You can relax your torsion bars if they are already cranked up and lose some of that 1.5" or you can go the other way and gain more lift.
Sheesh, I went and typed a whole bunch of stuff...
Let me know if you want any part #'s for the OME stuff or whatnot, I actually posted my price quote in a thread a while back that has all the part numbers for the rear lift I did. I can bump it so you can take a look.
Edit: Hard to say what is going on with your fuel gauge, all I can think of is try to get 12V to the dash wiring and see if it will go all the way up. Your oil guage should be a bit easier, check the passenger side of your engine and see if you have a terminal in the block that is missing a wire. It is either not connected and needs to be put back on, the wire could be all messed up and shorting out or you could have a bad sender in there. Easy fix either way.
Edit2: Here is the price quote for the rear end suspension parts I ordered, only thing missing is the rear shocks and the pin hangers that I picked up from the dealership (like 3 bucks each or so). I actually walked out the door paying $400 even so ignore the price total at the bottom, turns out shipping them to the store price was overquoted and I opted to pick them up from them. If you are anywhere near the place where I bought mine I reccomend these guys 100%.