I think target models were more likely than the regular version to be single-gun shipments on special order, but Shapleigh was a large dealer and could well have stocked a batch.

Now that you have a history letter, you can always request a record check from the Historical Foundation. You are charged only if they find something. The process is explained on the same webpage as the regular letter:

Smith & Wesson Historical Foundation - Home Page - Insuring that the rich history of Smith & Wesson will continue for generations to come