ford made 11 different part numbers for springs that fit mustang II and pinto. some of the racers used to put in 53 chevy springs but i don't know how they compared the factory springs specification =engineering chart had the various rate,unloaded length and ride height when they were installed. i had a copy to help a guy set up his pinto racer. if i would have known how popular M II suspensions were going to be i would have kept a copy. mustang II 's were nose heavy and didn't need as much castor as most street rods check with a few guys to see what they are running. if you change to power steering be sure to change or get a pump with the correct pressure output, ford and gm are vastly different in required pressure. good luck from a retired ford engeer