Preserving this cab art properly will take time whatever way you attack it.  Off course accuracy should always rule.  Guessing or cutting corners doesn't cut it, imo.  If your obtaining or building another cab.. there's no rush anyway.
2 ways to attack this imo.  You either trace it accurately with a good relevant paper medium and roll it away for a rainy day.. or you scan the artwork straight off the cab and compile the images via pc software.  I use Photoshop (raster) or Illustrator (vector).  
Photoshop manipulation of the scanned files will give you a large, raster, high quality file of the art you can file away or use however you see fit (decals, maniuplate for stencils)
Illustrator compilation is simply digitally tracing the artwork ... as you would with tracing paper and a pencil.  However in this case, we would trace the scanned artwork using PC software.  ie place the scanned artwork on the screen and individually trace every line/curve using vector lines, curves etc.  This then allows you to create different layers for different colors (ideal for printing mulitple stencils via print / signwriting shops) It also allows you to scale the image to what ever size you like without losing quality, as it just resizes the traced lines via algorithm.  This is how signwriters print f%&K-off sized signs so clearly.
Here is a good tutorial on how I use to scan artwork off cabinets, when I was involved in arcade artwork restoration .. http://www.rotheblog.com/2008/04/tutorials-arcade/scanning-arcade-game-sideart/.  Bit of a head f$%k ... but it works very well.
In this case, Photoshop is not as time consuming as Illustrator.  Both have their pros and cons, depending on a few factors... which is another story that could be discussed later if your interested.
Any accurate digital manipulation would still need you to measure x/y reference points (from vertical/horizontal cabinet edges)  on the cabinet art, so they can be used to check the digital files for accuracy.  
I could help you if you want to take the photoshop option (ie stitch, clean and compile the scans).  I don’t have time to take the Illustrator option though mate.  To much of my own shit to do:)
Cheers