You've got a thumbs up from me. I appreciate how simplistic the design is, it's definitely fitting for a car of this age. You don't tend to see a lot of overly itasha'd classics IRL so I'd say you've got it spot on. If I'd have to choose any areas to improve, I'd say to go closer to the Okudai liveries shapes that you based it off. Some IRL Skyline C10 itashas tend to go for those classic race liveries as their base design before their 'waifus' are slapped on top. Keep up the good work!
This skin is pretty nice. I noticed that there are some black spots in some of the panel lines from the image file for the skin. You likely left in the skin template when you converted the skin to .dds. Perhaps you can remove that to up the quality of the skin like I did for mine.