if you weren't against the jap engines i would say a SR20DET, RB26DETT, 2JZ-GTE would be the way to go (little ethnocentric but whatever floats your boat). to get a lot of power custom turbo would probably be the way to go, something like a trust T88. A benz engine would prob take a big shot of nos pretty well too, like a 100shot maybe 150. btw the real jap engines can stand well into the 1600+hp range, daily drivers in the 1000 range.