For chinese rubbers it is always the black one that is softer and has more tack. In the case of sanwei target national red, i had a sheet that is super sticky compared to the black.
I have asked a company if maybe they can reproduce the rubber since they also have esn rubbera. I hope they will listen. Those P7s were really something. Even with the polyball they would still be good.
Too many layers, too many things to adjust and c9nsider if you want to have a different outer ply from one side to the other side. Some company will probably do it but i dunno when.