Basically. I find and identify every wire in the diagrams before I decide what to do with it. If it's not needed, I cut as much of it out as I can (I usually leave about 3", just in case I made a mistake). If it will be needed but not the connector, I leave as much as possible, and coil it up and mark it with masking tape.
Yes, the EA81 harness is extremely simple by comparison, so just leave it as-is and splice in where you need to. There will be a half a dozen wires or so that are made redundant, but no big deal. Easiest to leave it all there to control body circuits (lights, dash, etc.).