Decals won't adhere to a flat finish, they need a smooth, glossy surface to stick well. Therefore you need to spray the red first, then lay down a gloss coat before applying decals. Some folks then put another coat of clear over the decals to seal them but I never have. If you decide to, test first to make sure the clear your using is compatible with the decals. Just a thought, you may want to tackle something a little simpler than the #24 for practice. That is not an easy scheme to complete, FWIW.
Thank you Harry. I know you don't do 1/24 but there are some interesting subjects in these old Heller kits. I have the Delahaye (as well as the fire engine), a 540K Mercedes, and the blower Bentley on the shelf. There are others I'm looking to snag on eBay.