The best advice I can offer when doing a NASCAR is take your time with the decals. The correct suspension and all are nice, but when it's on the shelf what you see is the body. They are moving billboards after all !
I've done dozens of both the Monogram and AMT kits, which is what got me back to building in the '90s. Start with good decals, either kit or aftermarket, and familiarize yourself with using some type of setting solution. Search the tips forum for topics on decaling, it's every bit as difficult as laying down a good paint job. It takes practice like anything else, I've got a box full of less than stellar builds to prove it.