To OP, you did it correctly. At least, as correctly as you could. People are dumb: without a full history everyone refuses to answer a simple question.
Anyway, 350whp is going to depend on a couple things. Mainly, fuel and dyno. If you stick to 91 octane I'd say go rotated. Definitely going to hit your goal with a 3076 (52lb/min) on 91. Plus, it's a great turbo for the 2.5 and you could always go bigger if you want or simply crank up the boost.
Safer option for the engine would be a 20g (42-47lb/min) variant (td06 8 or 10cm). Should get you close to 350 whp on most dynos with pump gas. Definitely with e85. Could just throw it on and have a great dd setup and say damn the numbers and enjoy.
Call the tuner you plan on going too, see what he says. He should definitely know what it takes to hit your goal on his dyno.