£20k won’t be enough. This might be underpowered, but gets you three engines, so you can strip one as a parts donor.
https://www.findafishingboat.com/yam...-x-3/ad-139566
Just powering it will eat into your budget, never mind renovate the stern engine bay or add in a couple of anti shock seats and a console. There’s also the small matter of a trailer. Break out another £3-4k.
Seriously though, I don’t doubt it’s well made, but it’s like trying to get an old Dakota airworthy again.
If Zodiac are involved that wouldn’t surprise me. They have their own MilPro division and have a habit of acquiring other manufacturers. Maybe more details here. Iceland based supplier. DSB750, but no build details.
https://isfell.is/en/vorur/work-and-mob-boats/
Have you actually visited the boat for an inspection? Is it a fibreglass hull or aluminium?
Not sure if the boat link is still valid? Was working last night.