Not having either units makes this hard to answer, so take this information lightly.
I know that the DX7 only had 32 memory locations, so I'm not sure if it sends program change messages above 32.

As the JV1010 is very much a preset unit you carn't even move it to a location that the DX7 can access.
Using a computer it should be easy, to do it from a old keyboard could be tricky.
Perhaps you should look for a second-hand JV1080, as this can store user patches, and performances.

Best I can do...