Is this as easy as I'm hoping? There are a lot of alternately messed up and functional parts I'd like to mix and match off both - I'm hoping everything's interchangeable and the ecu & harness match...
Please confirm.

86 Sport
Running engine / busted exterior

87 ???
Blown coolant seals? straight body

 

86 and 87 have the exact same ****. Harness is the same, block is the same, afm is the same. Its all the same. It wasn't until 89 that they changed quite a few things under the hood. In other words, its a direct exchange of parts between the two. Assuming they're both of the same type, ie turbo or na.