One of the last places I would look for accurate values for vintage guns is Fjestad's Blue Book. There is a much better source for S&W and that is Standard Catalog of Smith & Wesson, 4th Edition. This book was last updated with the help of dozens of members here and well worth the money. Do people complain about some of the values in that book, sure but it is a piece of work offered by two people who love S&W more than the money it brings them. Cannot say that about many other gun value books where they claim keep up to date about how much 10,000 guns are worth.
As far as your gun is concerned, you do not have a 1st Model, but rather a 2nd Model, 5th Change revolver that would be valued more like the 3rd Model than the 1st. The entry for this chamge states that it is the most common, bringing 20% less than the values listed for that of a 2nd Model, which are ANIB - $1250, Excellent - $750, VG - $500, and Good - $350. There is no premium for a 6" barrel listed, so one should not add a premium for the long barrel in the 5th Change.
Now what is the condition of the revolver you are going to buy? If it shows any wear, the value will be no where near $1000. Excellent is defined as 90% original finish, while Very Good has to have 70% original finish. Without detailed images posted here, you have to determine the condition and carefully apply the condition as detailed in the SCSW4.
While I was composing the original email, you added that the gun does not have matching serial numbers, so that fact alone relegates it to Good at best, so it is priced about right to 20% too high.
