I've broken down several old 1885's over the years to make customs. I've been taken to task for doing so on this board. My offer has always been the same: If the rifle is worth keeping as a whole, it should be worth the sum of it's parts.
Send me a MVA newly made (or C Sharps) receiver, a Green Mt. Barrel blank, and a Treebone or Crossno or CPA semi-inletted stock and I'll send you the old, tired original Winchester. I haven't had anyone yet take me up on it, and those rifles had a rebirth into something that has been used by me and my family as they were intended to be used.
I did reline one that is somewhat rare. I have an 1885 #4 barrel, 40-70ss, with known parentage tying it to Meachum and the last of the buffalo trade. It had no rifling left, and was a brown gun. I relined it with a quality, large diameter, fast twist liner and rechambered to a custom .40-70 chamber that allows it to use .405 brass. Invisible liner, and changed the appearance of the rifle not at all. I know that the rifle is not worth more with the relined bore than it was with the rotted out one; but everyone tells me what a shame that it is relined. If I hadn't relined it and tried to sell it, everyone would have told me what a shame it was that it had a rotted out bore. I also offered that rifle out for sale for the cost of a new reproduction, and had no takers.
I am going to have to build a new 1885 or two, as I had some stolen recently. I have new MVA receivers that I am going to use; not saving money by starting with a used rifle. I can afford to pay the rate to use all new and will on these rifles. Luckily, I still have the stock patterns; one of them was my wifes 1885 I detailed the build on a thread here a few years ago. The other was my .38-72, which I have been able to start the replacement of by buying a similar one on the classifieds here recently. It would be cheaper to start with an original rifle in decent condition, and rebuild it and sell the leftover parts than to start with new. So much for "collector" value.
Now on whether using the original to save costs is right, is debatable.
Let the argument go on.......