I been in the 5.0 mustang world since I was 13. The letter cams sound good and that's it. Yeah the ADVERTISE to make power in those rpms. But from experience, strap it to a dyno and show me it making the power. As far as the heads you have chosen for what you are wanting to do they are the 2nd choice stock head with the cobra gt40 non p style being the more desired but you will be fine with the p's and if you find them for $50.00 you better be jumping on that deal. I just think I'd look harder for a better cam. Cam motion for free if you email them your setup an tell them what you are doing will sen you back specs for free and an estimate on a cam, and you will be surprised. In my case on my new engine there custom ground camshaft was only 30.00 more than a comp extreme energy roller camshaft.