Resizing a Page in Acrobat Pro

I had to crop approximately 100 pages due to crop marks being included in the original PDF file. Is there a way to now get these pages (in a variety of page sizes, all smaller than letter size) resized to be on a letter sized page?

I've tried recroping the same pages back to the letter size I'm looking for, but it remembers the crop marks.

I'm not trying to enlarge anything, just center the existing page on a letter size page.

Thanks,

Peter