I also think that as far AR GTAs, both RHD and LHD, we on this Alfa BB, owners, historians are the experts.
You have made three points. First the owners are the experts. Second the historians are the experts, we on Alfabb are the experts.
I don't agree with you for all three points
First, an owner only has one car to view and cannot make generalizations about the other cars, they can rebuild their car to original FIA specification at best to get to 'original'. Owners have vested interest in their cars as being original, or more original than the next GTA that pops up. I would place little value on Sharp's comments or any other owner's comments when they make comments on cars not their own, as I mentioned before using one car to make general comments on 50 cars may not have any scientific rigor.
Second, even though discovery story of a GTA (one car) are important for example 'John said he saw car A when white, here is a picture at race track C and then it was red at race track Y was it the same car? here is a picture? You can not rely on this alone. When a historian/anthropologist conducts an oral history investigation there is a set process. Say 20 or more people are interviewed about a car they saw race on the 16th June 1966 at race track C, this constitutes oral history, many sources. (Using an oral history report to complement his application probably would have reduced the number of years it took Sharp to get his car accepted as a GTAm built by Autodelta)
Thirdly some times individuals on Alfabb pop up and say I'm an expert or I've looked at factory records and you want too much information I have it I will not give it to you (interesting).
Even though new books on GTAs have appeared lately, I'm not sure how they collated evidence for the cars.
So when viewing factory records for a book or other reasons someone in your team needs to be accredited as a licensed translator for Italian text written 50 years ago so you can read and translate the documents to derive the meaning intended in 1966! An accredited translated document is a secondary document but with some confidence it's an accurate translation.
As I mentioned before there are about 50 shades of RHD GTAs or even less so there is no point in claiming all cars should be mint and to original FIA specs when in fact we all know some cars were campaigned to the point of destruction crashed, highly modified and even hacked up and some rebuilt later!
I think the Alfa Romeo community has a long way to go before we can claim we have Alfa Romeo experts for any particular model including GTAs.
At least we can debate the process here on Alfabb in an open forum (on how to improve).