The chassis looks great Juan. Don't worry about hiding all that detail - if you follow the instructions you'll be able to lift off the finished body/interior to admire the chassis in all its glory.
The body doesn't look too bad in the photos, but if you're like me, the faults will draw your eye to them. I use Tamiya spraycans on nearly all my builds, the red is quite translucent, but the silver will cover anything.
If you decide you have to repaint, spray the whole body red, then carefully mask the roof. I use Tamiya masking tape at the colour separation line, and light-tack 3m (blue) for the rest. Apply a light coat of clear to seal the edges of the masking tape, then apply the silver. This will stop any silver bleeding through on to the red.
Good luck and keep going . My almost finished build from a while back: