The only bad thing about an 86 is the brakes. You would definetely want to get the newer spindles and brakes. The wiring harness will work and converting it to mass air is really easy the harness connector pins for mass air are open just plug in the two wires, 45,60 I think, then run an ignition hot and a ground, you can get a connector off of a lot of different mass air cars of course they need to be fords.
If you are going to use aftermarket gauges then this would work great, using the stock gauges your speedo would only go to 85mph.
1. How much is the donor???
2.Coverting to mass air is very easy, Although you do need a a9L computer and those are easy to find, I have one.
3.you would have to get new brakes and calipers.
4.with that engine you would have to get a bigger mass air meter anyway.
5. The 86 sender unit on the gas tank is upside down from the 87 and up, you would have to reverse the pins on the tank, otherwise you would empty when full, and full when empty.
6.If this car is $600-700 cheaper than anything else you can find then it might be a good idea.
Because all of the other misc. stuff is still the same.
So there's another opinion
Good Luck
Todd