you have the basics covered man stick with the smooth clean mods that you've got in mind and your car will turn out smooth and clean if carried through out the whole car like zen said
As for the interior, are you planning on going fast in your car? If so you might wanna think about a four poin roll cage, very subtl and maybe a racing harness for added safety, you don't need to put racing buckets in to have the harness so it should still remain fairly comfy
John