I'd look into the shoulder rigs from Aker;
www.DeltaForce.com , DelFatti(it's not cheap and may be out of service for a few more months), the Bianchi line, the Lawman Leathergoods STU(a standard black treated leather design/vertical carry);
www.Lawmanleathergoods.com .
I like the slanted carry style of the leather Aker model but like the options of Galco's Miami Classic II. I'd prefer a horizontal mag holder to free up more room on the belt line(for a 2nd gun/back-up or maybe a taser/OC spray).
Mitch Rosen & Greg Kramer sell shoulder rigs too but they may take months to get from the leathersmiths.