The Mustang 302ci and 5.0L engine are one and the same. Tell us the part no. of the cam so we can help you more. If the cam is specific for that motor, the firing order will be the same as for a stock cam.
2006 GT - 5MT - 12.74 @ 108.62 - 306rwhp 324rwtq (E) JLT 3 CAI, DIY CMDPs, Steeda UDPs, FRPP X-pipe, Brenspeed 91 tune