Getting ready to swap a 5.7 into my 73 Dart Swinger

Ok here lies the issue no spark and injectors not firing.. Swap specialties stamd alone harness is not worth the price alot of it was right wiring with wrong connectors i looked past it.. Now the wiring is the culprit. This is only my expirience it looked and sounded good amd dont get me started on the customer support..
Moving on i guess i got to start testing relays and fuses and chasing some wires.
Also started getting consistant pressure by bypassing the return line aka folding the *** emd of it in half and put a vice grip on it.