This is your ticket right here. A JDM 2JZ engine is about $2000 or less. Do the fuel system right, add a journal bearing precision turbocharger and a SAFC and you have this: 500RWHP daily driver. You can use the OEM automatic transmission or the 5-speed 1JZ trans or even the 6-speed Getrag, although those are quite pricey.
My favorite idea is the automatic trans with an upgraded converter and a mild shift kit. Dont over turbo it. This car is overturbo'd; The previous owner, Larry (teamorange inc), is all about numbers, not actual performance, so you will see 800rwhp 1000rwhp etc... all day in his cars but none of them will perform well without a 300 shot of nitrous and slicks. Dont over turbo it.