All it really needs to complete the Q-ship mission is white wall tires! Nice H-rated ones, maybe from Diamond Back. Make it look like your Grandfather's Buick. Oh, and ditch the extra gauges on the steering column. They ruin the esthetic of the sleeper.
No reason a Camaro cluster couldn't be utilized to make it more factory looking but retain the good gauges and the tach. A boost gauge can be MUCH smaller, maybe an 80s Chrysler piece from a Shelby Lancer or similar turbo K-derivative could be integrated somewhere stealth?
OK, now this is a sleeper! I have a perfect mental picture of my dogs G-forced to the tailgate window
I used to have that problem with my BB Chevelle wagon, as my Shepard would go flying! Had a 2" pad custom made, and would tell her to "hold on" - she'd actually dig her nails in on command! Without puncturing the vinyl. Miss that dog!!