Acknowledgement Page
If you wrote the original Acknowledgement page, and you still feel the same way about the help you acknowledged, then I believe that it is perfectly appropriate to use the same text. You are re-expressing sentiments that you had in 1997, using your own words. It is perfectly ethical to use them.

Beyond that, though, this would be a great opportunity to update the acknowledgements. "When I first developed the work in this volume, I was indebted to the following people ... ¶ Since then I have further benefited from ..."

Your decision to publish now, was it informed by your professional experience? Has your initial vision evolved since then, thanks to a stimulating work environment? Did anyone encourage you particularly to publish the manuscript?