i swapped my 87 dash for a 90 and the fuse location is in a different spot and the metal brace is different too if you want to mount the the plastic piece directly underneath the steering column.i think you will have to do some dicing and splicing to install your cluster but it probably would work although i never tried it.
I've been told the wiring for the gauges is completely different, but otherwise it's bolt in. Keep in mind a lot of changes happened between '86 and '87.
I responded to your build thread. There is A LOT of converting to do with very little information out there as far as the wiring goes. I have a harness that uses the plugs on an 86 from a 90's harness. I know that I got the bright light indicator, dash lights and turn signal arrows to work, the fuel gauge should work if you change you sending unit and I never tested the tach, volts, temp and oil gauges because I have mechanical gauges. The headlights, i used the new style switch and a relay and the wipers, I used another relay and a toggle because I broke my dang column switch. If you think it will help you, you can have it for the cost of shipping and the trip to Montgomery or come by and you can have it for free (Alabama).