Safest bet would be to just use the 87 long block and bolt all the 85 goodies to it. I know there was an injector switchover somewhere along the way (a high vs. low impedance thing), but mechanically everything should be identical. You could try to mix and match parts if you wanted, but for the most likely to succeed scenario, just switch the core mechanical parts.

My Truck: 1987 XtraCab DLX 22R 4WD 5 Speed Manual
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"Speed has never killed anyone. Suddenly becoming stationary, that's what gets you." -Jeremy Clarkson