The 1UZ into a MkIII is becoming a well documented swap. There's alot of details like the brake master cylinder, wiring, engine mounts, bellhousing, clutch... ect... that all need to be figured out. But, they have!
You can buy a bellhousing and flywheel from The Rod Shop. A brake booster from an early '86-'89 toyota truck or 4runner will move the brake master cylinder out of the way of the valve cover. The wiring isn't rocket science, people have done it... and most welding/fabrication shops won't charge that much to fab motor mounts.
The 1UZ sits further back in the bay giving better weight balance. It's substantially lighter than the 7M or 2JZ. It's also gaining aftermarket support: ITB's, superchargers, ect. 6 bolt mains and proven reliability and durability. Get tons of cooling upfront, change the oil often, and it'll live forever no matter what you do to it. I've also heard the stock ECU is good for 10psi of boost.
The 7M is a great motor, but if you want to bag the shit out of an engine at the track, you'll need to dump several bucketfulls of money into a 7M to make it last. Can it be done? Most definitely, and it has many times. Should you do it? That's up to you. For me, I would never spend a nickle to rebuild a 7M that broke... I'd get something else, there's tons of options for motors. For the record I spend alot of time, money, and research on maintaining my 7M and it's never let me down.