The upper intakes are different and can't be swapped.
The heads on the 86 are more restrictive.
The pistons on the 86 are flat top and limit the head and cam selection.
From what I've been told, the 86 block is the best block of the roller 5.0's. It has more iron.
Otherwise, the engines are the same.
Also, the EEC's are different (SD vs Mass Air).