I can highly recommend Bruce and his crew at The Desk Doctor.
VERY trust-worthy and knows everything about every SSL desk. On the side, he'll usually take on pretty much any custom project and either he or one of his guys will do it. In fact, he had plans for racking the 502's and 510's, already has CAD drawings, etc.
Give 'em a call and tell them I sent you his way, he'll be good to ya. (He's building a custom desk for me now)
http://www.deskdoctor.com/
Good guys. Really. (And this is coming from the guy who has already delt extensively with "that guy" over-seas. Not good)
-andrews
DIRTY HALO
www.dirtyhalo.com