I'd be good with Casas and Bello. I'd prefer somebody who isn't a 1B, but Casas is a legit middle of the order guy with both contact and power. Bello has three above average pitches with control. The Reds don't have anybody like that. For all the flash of Greene and Ashcraft, they don't have the change-up and Greene uses his Slider as his off-speed pitch but can't consistently throw it for strikes (when he does he's pretty dominant, but he just isn't that guy often enough).
I think that return would be near a best-case scenario, Adds a guy who might be able to replace Castillo and adds a potential offensive centerpiece.