I would suggest sleeving not only because its a good idea with that kind of power goal, but also just to keep you from using the block guard. Overall, if you want your motor to last, you'll need the sleeves anyway. GE makes awesome sleeves, AEBS is great too, but their service isn't so hot.

As for pistons, something in the 9:1-9.5:1 range would be optimal. As long as its a quality forged piston (JE, Wesico, Arias, etc), the make isn't so important.

Let me offer you a little advice for the block. If you're getting it sleeved anyway, you'll likely be sending it off to a shop to do the work (and I'm not talking your local machine shop). For only a little more than the cost of the sleeving, they can bore that motor out for you too. With the added displacement of 84 or 85mm pistons, it'll make those power goals much easier to achieve. It'll also spool your turbo faster, making it a blast of a daily driver. As for a place to get this work done, i've heard good things about camp1320.com and importbuilders.com, just to mention two.