Not in my opinion. I don't care for the scope personally and would add no value for it. Unless you just want a barrel that long then why not look into ordering a new one the way you want it equipped. If you just gotta buy a used one hold out for a price at least $250-300 less.
Not that the Premier life time warranty extends to other than the original owner but firing .45 Colts in the .454 Casull cylinder voids the warranty. Personally I'd pass on it. The missing cylinder plus the firing of .45 Colts in the .454 cylinder tells me the gun has not been properly cared for.