rotate singe page in multi-page tiff

 Greetings,

I am trying to find a way to rotated a single page in a multi-page tif file
using ImageMagick.  The background is that we need to pre-process tiff files
that will be faxed to rotated landscape pages.  I have tried using the
following command:

convert input.tif -rotate '90>' output.tif

but the problem this results in unreliable behaviour because the pages sizes
are not always 100% correct causing IM to make the wrong decision about what
should be rotated.  So I was hoping to write some specific logic to
determine which pages in the tif need rotating and the rotate only those
pages.

I've tried using the following post as an example but am really struggling
to make any meaningful progress:

http://old.nabble.com/Annotate-first-page-only-of-multi-page-tiff-td7684874.html#a7721659

Thanks in advance
Dominique