Ian,
I am not in the GCA business, so I have tried to provide an answer based on the realities of my world, which may or may not be palatable for someone in yours.
For the record, I would have a tough time not restoring an old treasure to its original state, but would rather get 90% there and do it myself, then leave it to someone else to get it 0% there.
In my industry, the consumer decides, and to succeed a company needs to provide the consumer with what they want on both an aesthetic and performance basis.
What is interesting, usually, is that the consumer does not always know exactly what they want until you show it to them. But what you give them needs to work with their original expectations.
If I am a big wheel on a Greens Committee, my priorities might be:
1) having a course that members can enjoy on a regular basis
2) having a course that will attract new members, and thus should be pleasing to guests
3) potentially having a course that can hold outside tournaments and thus provide good "press" and create street cred
For many golf clubs, adhering to or marketing the clubs history is probably not a top concern. It is a "like to have" but not a "must have".
Except in a few select situations, course or club history is probably not a sufficient selling point.
I want a course that is going to impress my buddies who are members at the new fancy Nicklaus layout or convince other friends that they should join my place instead of the new Fazio course down the street. My course can be authentic, but it still needs to be impressive.
If you want to sell me the idea of restoring my course to how it used to be, then an old black and white photo showing 4 dudes in knickers with a ratty bunker in the background is not going to do it.
You can sell me historical integrity if it is impressive. So impress me with kick ass graphical representations of what you want to do that look a lot better than what I thought I had wanted.
You may not be able to deliver exactly what Thompson (or whoever) originally designed, but what if you could get pretty close?
What if you could take his design, be honest to it, but make it viable in the present?
You have to write historical fiction, because a lot of people think that non-fiction is too boring to read. Be true to the story but make it suit your consumers needs.
If I need to see danger from the tee because that is what I expect, then show me a little flash, so my buddy from the office knows what is out there and doesn't call me an idiot for joining a club with invisible bunkers - while taking his initiation fee across the street.
Very few niche brands can tell customers to piss off and still succeed. Most who have tried are no longer in business. You have to be able to evolve with the times.
You can be true to the past, to its history, to its key principles, and still make it relevant to the present. My company does it all the time. History can be a powerful marketing tool, especially if you know how to sell it to your target consumer.