Simon, it's easy to see how the list can grow.
The Finns had the boat for many years and during that time, there were many advances in technology and new ideas to make wartime expediencies safer as well as old parts wearing out. So I'd expect many, many changes.
I've started a list of the changes I've made or planned to the Revell kit for my U-711 build. So far I'm up to 150 changes.
And even that is combining a lot of them together. For instance, I just put down "opening deck hatches" as one change, but in actual fact, there are about a dozen or more deck hatches that I'm putting hinges on to be able to open up and see the interior. So is that one change or 15 changes?
And since each hatch is scratch built, and each hinge, and the framework under the hatch, and the deck planking on top of the hatch, are those all changes too or just included in a catch phrase of "opening deck hatches"?