If your Target Model Bisley letters as you’ve described, it will command a substantial price! It is doubtful that it will identify the individual the gun was sold to, but sometimes with special orders a person will be identified along with the ship to information. Once you get the Archive letter and it confirms the configuration, there are many good appraisers that can assist you. As several have mentioned, with good high resolution photos of the Bisley, especially markings, we can give you feedback on the general originality of the Colt and an estimate of its value.
We all look forward to pictures as well as the contents of the Colt Archive’s research!