There is a big difference in restoration and upgrading. If I had a quality gun like the Colonel's 99 with family history, I'd have no reluctance to have someone restore it to what it may have looked like when a loved one bought it new. On the other hand, my understanding of upgrading is taking a G grade Lefever and making a fake Optimus out of it. I suspect the poster was thinking restoration and typed upgrade?...Geo
Besides, it would likely be cheaper to buy a hi-grade than to make one out of a worn field gun.
Although there is a difference between a quality restoration, and making a gun into a higher level gun; neither should be done to a gun with family history. Whatever condition the gun is today, it's history and condition were put there by his family. I'd be very sad if I passed my rifles down to my children and they sent them out and had them spiffed up to look like new.
I've purchased a couple rifles with the specific intent of restoring them, or even salvaging the actions for a build. But discovered provenance unrelated to me, but historically significant. Once I realized they had history, I simply did what I call a "sympathetic restoration" on them. I fixed broken parts, and repaired metal issues, and chips in the stocks. Tried all I could to ensure they did not appear restored, and maintained all the normal wear they had when they came into my possession.
One of these old guns is a Rolling Block Sporting Rifle that belonged to an early Oregon Pioneer who had nearly 90 years of serving the early Oregon Territory government, and was born in Oregon when it wasn't a state. If I'd restored the gun it would simply be another nice old Rolling Block.