[Jack21]

Assuming you're running a 302, or 351W based motor, open your Summit or Jegs catalog and order a set of Energy Suspension polyurethane SBF motor mounts, AND trans mount. They soak up high frequency vibrations, but plant engine solid.

If your car has newer frame mounts that use late Mustang motor mounts, it's a bolt in. (Single bolt, 14mm nut). If old style, you'll have to fabricate frame mounts.

Solves the header pipe to body, and air cleaner to hood scoop clearance issue quite nicely. Car (instead of engine) now rocks a little with engine idling.