I would put the 'default' revision number in the footer. This then allows you to only need the floating text box on those pages which have suffered a revision. That revision should be attached to the paragraph where the revision actually occurred.

Floating text boxes can float in a wide variety of ways. You can attach it to a paragraph but have it appear at the fixed location on that the page where that paragraph appears. If you select the text box and go to the text box's Layout Position and set its position RELATIVE to the PAGE.

__________________
Andrew Lockton
Chrysalis Design, Melbourne Australia