This is why I end up DIY'ing everything, I do a better job than random yard people
I would see all this with my own eyes before I did anything else that cost money. The pressure test is not beyond even basic DIY skills, even a caveman could do it
As for Beta diesel engines, the couple people I know that bought them love them. DIY'ing the engine swap will cost you double what a Moyer swap will cost you and probably triple at yard labor rates. The boat will be worth more at resale time, but not even close to what you will spend. Probably $0.25 on the dollar at best. The only reason I would swap over on my boat is if I have a need for a lot more range under power, which I presently do not.