I think it looks like a Zodiac F470.
Few give-aways, multiple D rings for lashing down kit, covers over the inflation points, built in bags/pouches. D rings on the bow for bridle towing, etc. My guess is hypalon as basically commercial grade.
Copy and paste this in to see user manual: chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://isurplus.com.au/manuals/Zodiac%20F470%20User%20Manual.pdf
Get in touch with your local Zodiac dealer, plenty to choose from state-side given you have the serial number:
https://www.zodiac-nautic.com/en/dealers/
Not sure what Grace is on about difference between PVC and Hypalon. If it was PVC, I doubt this sib would only have a small leak, especially if it's been stored outdoors since the 90s.
Better advice here from Polymarine:
https://www.polymarine.com/advice/pvc-or-hypalon/
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