We built up two Soma Double Cross frames with Fyxation Sparta carbon forks. They've both got Microshift Advent 1x9 drivetrains, Specialized Pathfinder 42c tires, Salsa Rustler Bars, SRAM Apex cranks, and Avid BB7 brakes with Avid Levers.
We have a 50cm (54cm top tube) and 54cm (56cm top tube). See the geo chart in the images.
Don't wait - our other custom bikes have not lasted long!