Yep, Callen is who you are looking for. A couple of us here have Callen shells. I know Scott Callen was having some major problems lately and I've heard tales of long delays to get shells. In fact, mine took a lot longer than it should have. Nonetheless, they're about the only builder around. They'll do whatever you want; cabinets, doors, electrical, lights, fans, etc.
Note, if you have them build cabinets with doors, supply your own hinges. The ones the put on sucked. The doors eventually popped open. Once that happened, the hinges sprung making the doors impossible to close.
Search on posts I've started and you'll find pics of the interior of my new shell.
John