If you have stock heads leave the stock cam, you will not gain any power with a new cam and any stock heads minus the GT40s which you do not have. All a new cam will do is move the power band and you actually might lose power.
2000 Mustang GT Steeda #0048 34k miles. 99 Cobra 4V swapped, FTBR IRS swapped, exhaust, tuned by James Gordon.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.