The G-10 sort of became a limited upgrade for older G models, though it was intended to be a stop gap new model.
Some were made with new air frames, which would be quite similar to the K4 when it finally went into production, some were G-14's finished as G-10's with the new engine, while others were upgraded from old or damaged airframes, featuring the cowl bulges and lacking other aerodynamic refinements of the K4. These later two would be the slower and probably more common versions, though still a fair improvement over the G-14.