Matt. I'm sure you've done your homework on the car in your picture (which is a Cabriolet A and not the subject of the Johan kit), but I have many detail shots of that car, plus many other 500K special roadsters. I can send you a compressed file if you can use Stuffit Expander or something that will work with Stuffit files (sitx).
Also, I suggest you go to Schlegelmilch.com for some excellent Special Roadster photography. Plus, we have a recent member on this forum (MAGIC MUFFLER, aka Billy Corbett), who does prep and maintenance work for Gooding and Company and their clients on the top classic Mercedes 500/540K examples they've sold.