Sorry being a day late but I had a little wager going on with a certain mod :p
Here is what I was able to come up with:
'86 was the first year for the Disck brake and in '88 the KDX was offered with the duel piston caliper.
PN for the '87 Caliper is 43041-1084
MSRP $271.31
Dlr Cost, $162.95
Pads;
They are different sizes for all years involved with the disk brake,
The interesting thing is the same PN's.
43050-1063
43050-1064
MSRP, $44.77 Each
Dlr Cost, $26.64 Each
The Software at work was limited only to Kawasaki parts so I was unable to locate any caliper that even remotley resembled what you listed.
Sorry,
Phillip