KK's top plate seemed to have a large outward slope.
The bolt position seemed fine.
The size of the rod bush seemed suspicious.
However, I have not actually installed the KK plate on the KJ and confirmed it.
It may be possible to install it by simply inserting an angle washer.
If the rod end dimensions of the RC shock are the same as the KJ's, it seems possible to replace only the top plate with the KJ's, but we won't know until we buy the RC shock ASSY.
It's a little scary that the total length is unknown.
If the overall length is long, it will cause inconvenience.
I probably still have both top plates so I can confirm the required dimensions.