No, people consider the Mustang II a POS, so just joking about the whole Mustang II/Pinto thing really and saying the 71 to 73 Mustangs are using the same parts as the Pinto 
I knew you were kidding

For the record I like the Mustang II, and I wouldn't kick a nice clean original one off of my driveway

You hit on it...the Mustang seats have thicker foam than the Pinto seats. A good shop can add more foam to fill out the covers better or you can buy new Mustang seat foam sets but they are pricey. Just make sure your Pinto foam is not breaking down because most are after 40 years. Turns to saw dust.
Yikes! The seat foam is expensive! I couldn't imagine an upholstery shop charging that much to shape new foam.
I just discovered there are 3 different options for seat foam and upholstery for the mustang. The grande has thicker foam than the standard seat, and the Mach-1 has thicker side bolsters. So just to clarify, my question only applies to the standard base trim mustang upholstery.