I dont agree with some of that.
The engibe had 5 uopdates in its lifespan.
The only really rare/custom parts i have a hard time finding/albeit not impossible are high quality aftermarket intake/exhaust manifolds. Have i ever had a 3sgte down long term due to utter lack of parts? No.
Power delivery, im not entirely sure what qualifies as good vs bad. The motor is almost like a 2/3 2jzgte. 2jzgte’s are heavy and very famous for being overengineered for substantially more power.
Stock ecu/fuel system on my gen 3, is good out to 300-330whp. My biggest concern is age of components 30 years deep. When all this stuff was newer, not so much.
Stock bottom end is good into 400 or450whp b4 i might start to lose confidence. Its an older motor, its co temporaries are 4g63, ej20, honda bseries, and sr20det. Some of the 4th/5th gens have oem chickenlegs for rods that id lose faith in after 350whp, i suspect thats where that tidbit comes from. Iirc the gen2s and gen3s are known for a robust oem stock bottom end for substantial increases in power.
Im personal friends with one of the foremost tuners of 3s/5sgte’s in the country, hes been doing it for 20 years…im curious how much he’d agree with what’s been stated.
Id prolly use my current car, its a 1994 mr2 gts. It gets the job done.