Well. Well well well. As it twer, I ain't a collector. Don't collect anything. The fore going just gives me a great Caveat: I don't care about the wood except it's really gorgeous. Much much nicer than what you would see from the factory in the day. UNLESS: The rifle was ordered and purchased as a presentation piece. That would also explain the engraving. I would be more inclined to think the swell wood and engraving were added post manufacture and I don't care.
The Mostest keyiest thing here is you have an Original (we hope) Central Fire 1866. Coolest of the cool. There were actually a pile of Central Fire 1866s manufactured. Unfortunately they were all packed in grease and shipped to South America and Spain. There may have been as many as a half dozen that escaped the export. "Most" Central Fire 1866s we see, here, today, were export guns that were acquired in south America, then re-patriated. Where the person you got it from, got it just doesn't matter. You have a really really way cool Rifle. All you need to do now is make some cartridges that will chamber. I believe 44 Russian cases will serve as parent cases (don't quote me) for modified 44 Henry Central Fire or one other cartridge whom name escapes me.
Atz just plain WAY KOOL!!!