Make sure that the 88 in question is truly an 88 model. The production date on the car must be between August 1987 and July 1988. If it's after August 1988, then it's really a 1989, and there will be significant fuel injection differences. NOthing that you can't correct by using the appropriate parts from your 87. Just be sure about what you're dealing with. One key item is that the distributor for an 89 has ONLY a rotor in it- there is no other wire besides the plug and coil wires, there is no hall pickup in there. That's the easiest way to tell.
If it's actually an 88 engine, then -zero- problems connecting everything up. Use it as it is.
If it's actually an 89 engine, you'll need to swap your 87 fuel injection components and distributor onto it. That's entirely possible- the castings are the same, you just need to be aware of the parts you would need to change out.
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Rob Bareiss, New London CT ::: '86 244DL- 215K, 87 244DL- 230K, 88 744GLE- 198K, 91 244 180K