Here's some names to throw out there.
Felix Hernandez: Not absolutely garunteed to get called up to stay this year. But there really isnt anything holding him back. He should get called up anytime after the all-star break, barring a major injury to the rotation.
Brandon Mccarthy: the minors K leader last year. Has really impressed this spring, and would have started in the rotation if Buehlre was injured as bad as originally thought.
Denny Bautista- Good pitching prospect, right now is the front runner for the 5th spot in Kc's rotation. so he may not work for you. Hes had a great spring and if he has learned to control his plus stuff he could be a huge pickup.
Scott Baker(Min)- Hes a lesser known prospect, but he did very well this spring and is next in line for a spot in Min. rotation. He is not really a power pitcher, more finesse but he does typically throw 90-93. And he also changes speeds extremely well, better than most in the minors. He could get a callup sometime before the all-star break.
Ezequial Astacio(Hou)-Another lesser known prospect who is having a great spring under the radar. He is also in contention for the 5th spot but is less likely to get it not because he hasnt preformed well but rather because of his age. And the Astros dont want to start his 3 yr. arbitration clock too early.
cant think of anymore at the moment, if i do ill add them later. But i hope this helps. drop a line when its done and let us know who you picked.