The SC300's 5spd was only an option til 1997.. then they discontinued it.
Some have black leather... but those are pretty rare.
Don't Quote me but I'm pretty sure the 1JZ never came with single turbo, They came twin turbo from the factory.
The 1JZ-GTE is a pretty good swap to do to these cars but the problem comes about when you try to source parts. Because the 1JZ was never offered here, parts are difficult to come about.
The w58 tranny found on the 5 spds should work with the 1JZ with no problem...
My suggestion would be to do the same swap i'm gonna do to mine... Swap in a MKIV supra 2JZ-GTE, the V160 (6spd) tranny, a custom driveshaft and the Supra rearend. These parts might be harder to find, and you have to do a little custom work on your wiring harness, but in the end its worth it.
The bare minimum to do a swap on this car would only consist of a MKIV harness, ECU, Engine, and some very small minor things everything else would just line up. A good used 2JZ can run anywhere from 2500 - 3500 dollars, the Harness can be from $300-600, and the ECU would be around 500. So total without labor, figuring in minor things would be around 5-6kish for a bare minimum swap.
The 2JZ-GTE is a proven platform to work with here... people are still making massive hp with these engines, the engine is bascially limitless... but it all depends on your goals, and what you want to do.
The stock 2JZ-GE can be turbo'd also for some decent power, its a great alternative. :D