I think Raps already have their rim protector, it's Amir Johnson. He is called "Dr. Of Denial" for a reason. I just think it's better to bring him off the bench as a back up C/PF.
I'm not sure who they should pursue as a big wing player but I'd prefer the Raps pursue someone younger. Tobias Harris comes to mind for me,not sure if the Magic are willing to part with him though. I think he would be good under Casey and fit well alongside DeRozan or Ross(if they had to move one but ideally it would be better to keep both if possible and bring Terrence off the bench as a 6th man).