I think your last post is on the money. Having lived with several of them in the past, a solid lifter cam is a PITA for the street, unless you just really enjoy adjusting valves. Cam technology has come a long way and a hydraulic or roller cam will give you all the performance and RPM you need. Get a rear end gear to let that big block do what it does best, torque in the drivable RPM range, and you will give those Mustangs fits.