It's clear that you are the one who doesn't know anything about motors.... That Supra is amazing and a 2J is an excellent motor but there is no way in hell that motor is running stock anything. For that amount of boost valve springs (probably valves too), pistons, probably crank shaft had to be changed, the head had to be ported and extruded at minimum if not a completely custom built head, the cams were changed and the block was likely resleeved.
For the RB to run 1000hp reliably the same things will have to be done, you cannot push the motor to over 3x stock power w/o doing serious work. That N1 motor was built for racing, they are strong but as all racing motors it wasn't made for huge reliability. Why do you think the Z tune GT-R runs "only" 510hp on that block despite having more displacement? Here is a hint, it's not because Nissan couldn't make it produce more.... A huge reason for such "low" power output is reliability, this is one of the reasons why so many cars are so easily tuneable, the cars are made for reliability, if the motor is running at 50% of what it can do it will last for a long time. No motor in the world runs at 25% of its capacity though....