the NA motors (2JZGE) will handle 400-500RWHP all day long on stock bottom end, proven.... and good for 600+RWHP. Which many can agree that is DAMN impressive for a street car.
This is quoting Dave H (well known Supra owner) -
I've ran my same engine na-t for uhhh.... years now. Around 5 years if I recall. I usually run ~450rwhp on the street, and have ran 600+ rwhp on the dyno and track. The engine has been flawless. Mine engine is completely stock except for a 3mm headgasket and ARP head studs.
So if thats the route you want to take, a nice street turbo setup.. then this would probably be a good choice - if you like the Supra that is. You can always save up more and get a TT.