The Marti by the numbers book has factory (not dealer) option break downs by body type, but Machs are included in Sportsroofs, so Machs, Boss 302s, and plain sportsroofs are all in the same group. Rarest option for a sportsroof? Speed Control.
To my knowledge there is no central data base that tracked the installation of dealer accessories so you are probably SOL on that one. On the factory installed options, most folks with '67-'73 Mustangs will contact Kevin Marti for a report based upon Ford's database (which Kevin owns) Depending on what detail of information you are looking for, you can simply confirm original equipment or go all the way to a statistical breakdown often leading to the "one of one" status. Kevin is a member of this forum.
In my experience, cars with 15 or more factory options seem to be the "well optioned" cars.