i've seen the original picture of your car around the internet for years. it is actually posted a lot of places. i've had a copy of this pic for years now.
i own a M-Code fastback that i am currently working on. you mentioned that your car has several "unique" options like functional hood scoops and hood pins. i have never seen or heard of a 69 M Cuda with functional hood scoops. could you post a picture of those? and it is my understanding that the mopar hood pins did not come out until the new and redesigned E-body Cudas for the 1970 model year. as to the hood scoops, i have a set of original OEM scoops for the M car (the same ones also used on the A56 and A57 "Cuda" package) but i would never cut them up. i'm going to buy a set of reproduction scoops and modify those as functional. i would be interested in seeing how the scoops on your car are designed under the hood.
the "slick" back top option was indeed, "very rare". there have been a few fastbacks advertised with this option but the ones i've seen were black not white. you might have the only white "slick back" Barracuda out there.
you have a very nice car. it will be great to see it when it's done.