Brian, nice to see you on here!
Here's my two cents...
There is really no way of making a '69 Camaro with all DSE components, etc. look like a total sleeper. I mean, it is going to sit 3-4 inches lower than stock to begin with, and in my opinion, a car with that kind of stance looks way too intimidating to be stock. Down the street, Hot Rods built a '69 for a customer who wanted the exact same theme as you. Inside it had a vinyl interior with original seats, and under the hood it had a supercharged LSX making 700+ horsepower. It also had 19" HRE wheels, which became a dead giveaway that it wasn't an ordinary Camaro. It looks exactly exactly the way the description reads, which is a hot rod with a stock interior a clean body. When I saw it the word sleeper did not come to mind.
At the end of the day, people who are interested in cars will know that you've got something really special, and people who aren't interested in cars often won't know or care. So, If it were me, I'd take the retro, understated theme, and apply it to everything. I'd get some wheels like this:

a pair of real comfortable seats that are simple and not race-car looking, and paint the car that Jaguar green because its an awesome color that you like. When you guys are all done with your car it is going to look so shiny that even a stock '69 color would look different on it. Besides, that green is an understated color which doesn't scream custom from 30 feet away like the 2010 Camaro Synergy Green does when painted on an old Camaro.
Matt