You ALWAYS do a boroscope inspection on every single M96/M97 engined car you intend to buy. If you spend a few hundred quid across multiple cars, then that's better than buying a car that suddenly needs £7K worth of work a couple of weeks after you bought it. You don't do it on every car you see, only the one you intend to buy.
You can only do so much on a visual inspection like you say, which is why you check everything as much as you possibly can and THEN you get the boroscope or full inspection (depending on your own mechanical knowledge) done on the car before you hand over a penny. I'm not trying to be an arse here, or do the old I told you so, I'm merely stating common knowledge that absolutely every single person with knowledge of these cars will tell you to do. I've seen so many people across so many forums take their cars outside of the big names to try and save a few quid, only to find the repair was done on the cheap to low standards and with only a few of the bits that needed replacing doing.
Again, I'm not saying that's what's going to happen here, and I'm actually really curious to see what does get changed and what liners are used as it would be great to know of somewhere more local to me that I could use for when I buy my next Porker. I really want this to be a success, but to imply that I don't know what I'm talking about and that I'm talking sh*t just isn't fair or true. You knew the history of these engines before you bought the car, and you didn't do what everyone tells you you should do. You took a gamble and sadly you got caught out, and I feel sorry for you, I really do. It's a beautiful car and it deserves to be up and running on the road soon.