I am no expert but I believe if you simply add the 280 complete with harness the dist and alt can still be run by the 240 harness, the 280 has 2 harnesses one for the injection and the other for evereything else, as for addl goodies, you'll want the 280 fuel tank as it is fitted with a return line from the fuel rail, you'll also want the return lines themselves or buy some tubing and make your own, the fuel pump is in tank I think ? (not sure) havn't got mine apart that far yet, the wiring to use the fuel pump is already in your car under the passanger seat carpet, the jap model used an electric pump even on the early models, goodluck