If by "roadster geometry" you mean a slack (66-68 degree) head tube and seat tube angle I think you might be out of luck for anything commercially produced. The cost of creating a wide variety of investment castings and distributing the product is high and the demand is minuscule. You might look into TIG-welded custom lugs, such as those made by ANT bikes or by Mark Nobilette as described in Bicycle Quarterly vol. 4 no. 4. This ANT-built bike appears to be an example of a roadster geometry frame using custom lugs. Most of the examples of bicycles I've seen in this style appear to have just very simple tubular lugs rather than anything particularly fancy.