Thanks for the comments! 
The farthest the Germans went with this design was getting plenty of wind tunnel data to perfect the flying qualities and I believe a mockup of the cockpit was built but there is not much other information available.
The Soviets were known to have interest in several of the Junkers designs and some like the Ju 287 was built and test flown with an interest in equipping the Soviet airforce with it as part of its bomber fleet and other designs like the Ju EF 126 were built for pure research AND to deceive the spies of the western powers as to what fighter aircraft the Soviets might be developing. The Ju EF 126 was pretty much a dead end design wise but the Ju EF 128 was quite a different story, the blueprints were complete and only a lack of resources and time prevented the Germans from completing any prototypes, the Soviets not only captured all the Junkers material on advanced aircraft designs but many of the personnel as well. Some Junkers facilities were actually torn down and rebuilt brick for brick inside the Soviet Union and engineers were forced to live and work deep inside Russia to develop the Junkers designs for possible use by the Soviet airforce.
Right now I no proof the Ju EF 128 was built but nobody can prove it was not. Sadly the way world events are unfolding the chance of finding out the full story on the Russian use of German designs in the post-war era will never be told.
Matrixone
The farthest the Germans went with this design was getting plenty of wind tunnel data to perfect the flying qualities and I believe a mockup of the cockpit was built but there is not much other information available.
The Soviets were known to have interest in several of the Junkers designs and some like the Ju 287 was built and test flown with an interest in equipping the Soviet airforce with it as part of its bomber fleet and other designs like the Ju EF 126 were built for pure research AND to deceive the spies of the western powers as to what fighter aircraft the Soviets might be developing. The Ju EF 126 was pretty much a dead end design wise but the Ju EF 128 was quite a different story, the blueprints were complete and only a lack of resources and time prevented the Germans from completing any prototypes, the Soviets not only captured all the Junkers material on advanced aircraft designs but many of the personnel as well. Some Junkers facilities were actually torn down and rebuilt brick for brick inside the Soviet Union and engineers were forced to live and work deep inside Russia to develop the Junkers designs for possible use by the Soviet airforce.
Right now I no proof the Ju EF 128 was built but nobody can prove it was not. Sadly the way world events are unfolding the chance of finding out the full story on the Russian use of German designs in the post-war era will never be told.
Matrixone