For acquiring minimal data needed to define the geometry, it may be better to use the various TryGet… methods of Geometry.Curve and Geometry.Surface and this code for boxes (PythonScript equivalent of IsBox and BoxPoints? - #2 by dale). If a shape is found, use its properties. Any additional data that the other CAD system requires would just have to be calculated, like what Dale provided for an Ellipse. This may also be the case for Cylinders and Cones so that their Height values reflect the referenced Breps.