Nope, you can use the stock coil pack and module. A lot of people swap them to 87, or at least the coil pack, because if it does fail, 87 coil packs are cheaper. And you can get a high performance coil pack for about $60 for 87!
If you swap to 87 ECM, do the ECM, MAT, MAF then drive it for a while. I haven't swapped to the 87 coilpack yet, but may in the future, especially if the pack goes out. Do like I am doing, find the coilpack adapter plate, and adapter harness used or in the parts for sale section, then convert later. I have the plate, got it for $15 shipped. I am getting the harness adapter for $25 shipped. Then I can keep an eye out for an 87 coil pack used, or pay $60 for a high perf one, new. Sure beats $250+ for an 85 coil!
Let me know if you have any other questions. This board is all about asking questions and learning about these cars. These guys are a HUGE help!!!
Squid