I don't know you or anything about all that ^^^ but don't grade the marketplace on your current quest. What you're asking for is the rarest of rare, as it's only (apparently) available in the OCD. Supply will take a while to build, but this will show you how daunting this task is:
From Cryptomanic's thread:
https://www.gtplanet.net/forum/showthread.php?t=218649
Chevrolet Camaro Z28 '69(STANDARD ONLY)
ALL COLORS COMPLETE-Butternut Yellow-Burnished Brown Metallic-Burgundy Metallic-Dover White-Tuxedo Black-Hugger Orange-Olympic Gold Metallic-Glacier Blue Metallic-Cortez Silver Metallic-
Azure Turquoise Metallic-Champagne Gold Metallic-Garnet Red-Dusk Blue Metallic-
Fathom Blue Metallic-Daytona Yellow-Forest Green Metallic-Lemans Blue Metallic-Rallye Green Metallic
That's 18 colours to make the full set (so far) and I haven't asked him, so I have no idea that all those are even available as of yet in trade (I suspect the presentation means just that, but I won't promise someone else's business), and all from a vehicle who's only gotchya-point so far is one showing in the OCD that I know of. I got one when it came up (I get every classic I can lay my hands on) and, not realizing the difference from the '69 SS immediately took it to the shop and tricked it out, thus losing the ability to hand it over for a bit to someone who would replicate it and thus increase supply. Oh yeah

So just know you're asking for one of the rarest vehicles ingame so far and instead of sitting in your own thread waiting for it to drop out of the sky, you could end up quite happily surprised by going where the cars are and making deals:tup:
On the question of painting this car, No you can't. You can put rims on it though, just like the SS. No aero.