Setting Page Margins and Rotation of Pages

I have scan book with my mobile camera, I have cleared background in Photoshop by applying Threshold to it and make it ready for PDF book. Now my problem is when I navigate to one page from another, the image size, and rotation are not constant, but they vary page by page. and of course this is because I have taken picture from one angle then from another angle and also not from the same distance. I want to set all the images (which is now Text, on image. Text is not enlish but Middle East Language) on center of Letter page and when I navigate to one page from another page, I want a consistent look. Thanks

PS: If you are unable to get my point, I will show you my work.

[Fawad Iqbal]

I want like the image attached, I want all pages to be enclosed inside the blue guideline. If you guys help me in any way, please do it, i will be more than happy. Hoping for best

Fawad