I don't think preview can do what you are asking. You might need to have Adobe Acrobat, which can rotate individual pages and - with add-ons, individual images or text. I'm not sure if Acrobat Reader can do this, but - since its a free download I suggest you download it from the adobe website and give it a try.
If this doesn't help, you can rotate it in Illustrator or at worst Photoshop and re-import the page back into the file. of course if you open the page in Photoshop, you will be in effect rasterizing it, including the type.