JZ in a box lancer? Spending lots of money turning it in a drag car will make it hold traction, but for street, forget it.
Independent systems aren't that hard to work up, and from experience, you have more better control feeling with them.
This is what can happen with a properly setup engine, working well and not seeing about your rear end :
That was basically a stock 1jzgte, air filter ran to the front of the grill, 3" exhaust, walbro external fuel pump, bigger fuel lines, 3" piping with front mount intercooler, automatic tranny adjusted a bit(dunno what the guy did). Could have only gotten high 14's bcuz of slippage at the rear. After the independent rear on my car, i was able to boost a little off the line properly and hit a 13.7 with just 11-12psi boost and a few adjustments on suspension.
MK3 independent system or cefiro system, can work really well. Lining it up is the real major problem, but it takes nothing more really. Drive shaft work and exhaust passing under or over it is not big scene. In my case after the independent setup which took only 3-4 days, the car seated nicely, i had gotten tien coil overs with it and i used back cressida shock mounts and it was set nice. Car stayed straight, never had a problem with it ever since and it basically solved my rear end of the car problems.
Also the royal saloon diff with rear discs i heard is a good replacement diff if you don't want to go independent rear, but im not sure on suspension wise. I'd recommend doing an independent rear, spend a little extra, than having to get a headache for suspension and brakes.
Front suspension, on some cars, have similar bolt ups for many coil overs if u want that. Just reuse back shock mount of remake the bolt up area by re-drilling holes. Doing this however, i would recommend you make a plate both on top and below the original body you are drilling on and those plates should only have the bolt up of the coil over design.
This is to keep it a little more stronger and prevent that area weakening.
Most people use 300zx or skyline rotors and calipers, some say its easy to workup, some say no lol. Supra brakes from either mk3 gt or mk4 turbo or non turbo are good upgrades, but are hard to find. Depending on you car you swap it in, you can use whichever.
Drunk 24-7 has shared a lot of great wise info which is extremely good info in my opinion. I had my share of smelly brakes every time driving.
1JZGTE & 2JZGTE's does not need BIG SETS of modification for power, its who you listen to and the right basic parts you use. Like most of them away use this term, BPU (Basic Performance Upgrades).
Toyota transmissions can hold up to 450hp, but a very safe item to put, very cheap too, is an aluminum transmission oil cooler. I've had one, never regretted it for the abuse the transmission took and was still kicking when car was sold.
Had experience with 1jzgte and 2jzgte, both/each automatic and gearbox. Never had any parts fail on me, nor sensors.
If you want something extreme, a nice upgrade would be an extractor manifold, something more on the sides of a t61 turbo or so, some 550-720cc injectors, greddy emanage ultimate, exhaust work, good intercooler, good clutch and you'll be happy with 15psi daily.
This is from a setup i know of, and it makes 458rwhp out of a 1jzgte. Uses cams from the US model 2jzgte however, before those cams, it did 422.
Heres the setup and car, MK3 Supra, running 19" rims and 285's at the rear, and still not holding much traction. Automatic too!
Anyone need help with more JZ stuff, give me a shout.