The JP D-Sonic has the "bar" blacked out, while the other pole pieces are still silver. Off the shelf models have a chrome/silver bar and pole pieces. Otherwise specs are the same.
I don't know if DiMarzio offers the D-Sonic with a black bar as a shelf piece, they very well may.
That is the correct way to do it. You will need to take the scrap wire from the D-sonic and use it to lengthen the leads on the neck pickup, otherwise the wiring isn't long enough to reach the toggle when you rotate the pickup.