In terms of the available information, I'll just give an example of a hole where I think that Tom and his team can get the accuracy nearly perfect. The available information and high resolution photos varies across the site, but there is a really good baseline, even for the holes with the least amount of info, mainly because of the detailed plans, some high resolution aerials, and some decent resolution oblique aerials.
Here is an assemblage of information for #3 (Eden). When building out each hole digitally, I'll just collect everything available for a hole, including all the writings, and try to make the model match from all angles to a reasonable level. I would expect that my digital model would provide the rough draft and then Tom and his team would mainly work off of the actual source data when they are trying to dial in the accuracy. They surely won't be able to get it to the inch, but hopefully they could get it to a level where a member from the original Lido wouldn't notice the difference (ignoring the new setting).
SROLL RIGHT TO SEE THE FULL IMAGES
(in this pic, the guy must be a very reliable ball striker for the caddie and his wife to stand right there.)
This photo gives some clue as to the back edge of the green, especially in the back right corner.
In photos like these, it's easy to focus on the foreground. But this provides great info for #4 as well.
Same pic, but a different cropping and it shows more of the front of the green:
From George's book: Great look at the fall off in the front left. And People in the pic give a nice size perspective. But notice how the front-right part of the green differs from the pic above. Also, the bunker face differs from the view from the tee. Those are examples of the things that Tom and his team have to sort through and decision.
Oblique aerial from the Channel side- this perspective is really great for holes on the North half of the course. You can see the diagonal ridge for the falloff that matches the pic above. It also provides a really nice look at what happens over the green and the lips of the traps looking back toward the tee.
And some vertical aerials- these weren't that helpful for this hole regarding contours, but are for others. And they were critical to get the fairway lines, green edges, and bunkers right in a 2D sense. The only tricky part was that some things changed slightly from when it was built to when some of these were taken, so I had to be aware of those changes.
Negative- which can sometimes reveal things that I'd otherwise miss.
Luckily, this was such a famous course that there were lots of photos taken. I am hopeful that we can uncover some more over the next year. The aerials that Craig Disher provided were a huge help and he continues to find higher resolution versions.