Ah, Peter, please don't stay in your darkened room for too long -- we love your posts, wisdom, humour, wit, and angst included ;-)
The question of what is the "right standard" for restoring a gun is one that will never be resolved, no matter how long we debate it. (Believe me, this is not just a question for gun restorers, it is a question that is similarly debated by antique furniture, auto, house, and boat restorers too. You could take all the debaters and stretch then end-to-end around the world, and they'd reach to no conclusion. (Peter, this means you may spend a lot of time in your dark room -- not something we want).
It reminds me of the debates that happened when I was restoring 300 year old houses. I'd have an open house for restoration friends who represented different "schools of thought" about what was the proper restoration approach (what era to restore back to, what authenticity of parts, etc.). These debates got so heated at time, I'd start to "bait the purists" whose philosophy, if taken to extremes, would have me living in an "authentic" 17th century home -- with a privy out back, no running water, no electricity to run my computer, and a wife who'd want me buried in the back yard.
I have my own "philosophy" and set of principles (which I won't foist on others, but will share):
1) it it's a gun, be sure it's safe if someone might shoot it in the future. If it's not safe, be sure it's marked unsafe.
2) like the armourer, use authentic parts, if available; if not available, use 1st class reproduction parts when and if necessary
3) all repairs and upgrades (like putting a better sight on a gun) should be authentic to the period
4) if the gun represents an positive evolution (i.e. a No.4 Mk1/3) retain the highest grade evolution, don't take it back to original,
except if the evolution was detrimental (such as a sporterized version), then restore to original. (believe me, this principle is always going to be controversial.)
5) if in doubt as to what to do: wait, do nothing, research, ask for opinions, and "let the gun speak to you."
6) more often than not, less is best, except when it comes to safety.
7) write a provenance of the gun -- where it came from, how I found it, and what I did to it -- so that a future collector isn't confounded, bewitched and bewildered
8) never present the restoration in a fraudulent way that would be considered a "fake" that was intended to deceive
9) restore a gun because you love the gun and the process of revitalization, not simply because it's a "money maker," (but making money doesn't hurt and isn't bad)
10) don't be afraid to take a really good restoration technique from one field and use it in a similar field if it serves preservation a hundred years or more from now.
11) spread the wealth of knowledge: share what you learned with others -- "collecting" doesn't mean "hording knowledge" -- which is why I love this Milsurps community.
12) graciously thank and acknowledge those who have contributed to your learning and your sources of insight.
This is my approach, and I'm sure everyone on this site has theirs. I find it useful to make restoration principles visible and overt, so that anyone who acquires a gun I've touched knows what went into it -- what it is, and what it isn't.