I can't recall what rotors are on the front of the 87 Hardbody.
Vented or solid?
If you have solid rotors there is a very good chance the Brembo Calipers from the 2000 series of SEr Sentra will work. I know for a fact that the Brembo's are a direct bolt on to my 2000 Xterra and I beleive all of Nissan's D21's, Pathfinders, Frontiers and Xterra's up to 2004 use the same 2 tab bolt pattern on the steering knuckle.
Here's a thread I am working on for doing Brembo Conversion on my Xterra. I have some measurements on there that might help you.
zerothread?id=207086
The other option you might want to consider is getting a pair of Calipers from a 4x4 Xterra or Frontier (2000-2004). The 4x4's used a dual piston caliper instead of the single piston your D21 comes with. It should be a straight bolt up. The spacing on the 2 large bolts that secures the cast bracket to the knuckle is 4" for the Xterra. Then the caliper bolts to the bracket. I can send you some images of the Xterra's Front Brake assembly if you're interested.