Hi Kurfürst!
According to Mueller "Junkers Flugtreibwerke" (Junkers aero-engines) and Gersdorff/Schubert the jumo 213 variant wich had a higher compression ratio and could use c3 was the 213b variant. But this engine wasn't put into series production and no d-9 was equipped with it.
Did you own these papers? It would be very interesting to have look at it.
Greetings
Thrawn