Nice work so far Toshi.
Just a few more suggestions for you.
1: The seam on the barrel could use a little work
2: When you come to weathering, the mufflers (the box-like structures on the fenders at the rear, either side of the engine deck) could use some rust effects. They got pretty hot and the paint burned off them. You can get an idea of how this looks from the box art.
3: On the left side fender, there are three sprue nubs left over from the manufacturing process. A few swipes with a sharp blade & some fine sandpaper will take care of this. Just beware of the two tabs on the muffler, they should be there, like on the other side.
Keep up the good work..