hi friends, i have a 65 gmc that had a 230 6 cly in it. i replaced it with a 283. i ordered the wiring harness for engine bay from brothers so i could plug up my new hei dist. the truck cranks right up with switch but will not shut off. i didn't have this problem until i changed engines.I have tried chaning the two wires in the harness around. one way it will not even crank. whats could be going on?