A few weeks back I spoke with a woman in a GREAT looking Sprinter parked in the Newbrighton State Beach parking lot. She told me that it was a ground-up build by Happy Vans in San Jose. A few days later I stopped by Happy Vans and checked out some of their other work. They do a great deal of work vans but had done a few ground-up builds and a few remodels.
With that said, I haven't had any work done by them myself so I can't give you a definite recommendation.
ps. They're van builders and not webmasters so their website looks like it was designed back in 1992
Best of luck!