Sorry to hear about your Dad, a sad but inescapable end for us all, and I think it's good you related your experience with the club,
Not surprised at all by your story, I have had several interactions with club experts issuing what I've come to describe as "personal decrees of fact", only to remain silent even after seeing conflicting factory documentation produced in some instances. Generally there's a good bunch of guys involved here but I've discovered that regardless of someones reputation as an "expert", their opinion should be consider only an opinion without the documentation. I could extrapolate further, but suffice to say, we're all getting older, memories get spotty and egos find it hard to take that bite of humble pie we all inevitably create, while it's early, and still small. Your story and experience is not unique to this club from what I read. It seems common to some other clubs too.
I too am restoring a car, now with my grandsons. Even though it's mostly correct, there are numerous small details that are not, that likely would be noticed by most "dyed in the wool" Aero guys, some I'm sure I would have to point out. No doubt some experts would gleefully point them out to everyone that will listen, almost yelling "citizens arrest!" Barney Fife style, others nodding in agreement as to why the modifications were valid.
I'll probably do the annual local show organized by the painter at the VFW, maybe one of the Kaiser-Frazer shows or Midwest Willys shows if they ever land close. After I'm too old or gone, the boys can do what they want with the car, or join wherever they feel welcome.
Savor the time you and your dad spent together rebuilding the car, the shows you attended, and the satisfaction you shared where your project was unequivocally welcomed and appreciated for what you two did together. Regardless of what happened here, those memories are priceless and irreplaceable, many wish too late that they had them too.
The fact that your car brought 40K, even for a good cause says a lot. I highly doubt that no "expert" here but a Darrin owner would risk more than a few paltry dollars betting that their car could garner anywhere near 40K at an absolute auction. You & your Dads hard work went to support a good cause.