Stick with the stock turbos and you'll have heaps of power developing UNDER 2,000rpm . But then, stock turbos won't make your 400rwhp.
Just do basic conversion for starters (maybe improve intake/IC and exhaust if you can), and drive it. Many people doing 1J conversions start much as yourself, planning a stage 3 and four of development before finishing the basic conversion - and are plesantly surprised by the power you can squeeze out of the stock system. When that gets boring - you can upgrade componants as needed.