I wouldn't worry too much mate, chances are its only the fuel pump wiring. S2 ecu's will run on a S1 but its best to have the right ECU's, your ignition ECU should be Blue Red Blue colour code IIRC, and the fuelling ECU should have a blue sticker NOT a green one.

Theres a brand new fuel pump relay on eBay, and the plug is the same although the wires need moving, and one extra seperate connection on its own.

If you were closer i'd help you sort it out

Anyway before you even worry about that too much have you got a quick blow fuse and tried it yet??