Hi Mike. For what it’s worth: I used to manage a 35m research vessel (Vanuatu flag) - we put a MK1 Pac22 onboard. Certification required was minimal (joys of said flag state). Doesn’t really help your situation but it can be done!
Might be worth talking to these chaps (this website is their other business) - they buy and refurbish a lot of Pacific’s from the MOD (we bought ours from them) - they may we’ll have or know of where you can get the paperwork you need:
http://www.plymouthboatpark.co.uk/contact