vtec wiring on a p28 ecu

[THEONE]

i found otu today from the previous owner it has been converted to obd1 and the car runs great as it is but i would like to have vtec hooked up to finish it off aswell as the 4 wire o2 sensor. the o2 was hooked up but from many diffrent motors swapped in and out of the car we are not sure what happend to the wires going to the ecu. oh and thanks for the diagram. that helps. i want to be 100% sure in what order do the plugs go as far as a,b,c,d i know how they plug in i just need to be sure i working with harness a or b or whatever and i will need to run my own wires to the ecu because alot of them have been removed or are just not worth messing with.