Just zoomed in on the side art as much as possible. It appears to be original. You can tell because the lines are "blocky". They don't taper at the ends.
I will see if I can find the thread on KLOV with pictures illustrating this.
And it goes without saying, if the side art is originaly, it is very unlikely it has been repainted.
:edit: I had it backwards the blocky ends of lines, particularly at the hands, are repro. This link has good pics of NOS, start on page 5. Post 57 has good pictures comparing DK's hand across original and a couple repros.
http://forums.arcade-museum.com/showthread.php?t=271671&page=6At the end of the day, this is probably a bit of over-analysis. From what I see, the cab looks to be in really good shape, mostly original. If the price is right, and unless something really sticks out when you go look at it, it looks like it could be a keeper.