The rotors have a minimum thickness cast into them, bring a set of dial calipers to measure them. Minimum is something like .920 If the calipers are still painted, they're likely still good. I recall one set I bought had everything nearly new and paid $75 for the whole setup.
I'd look at a kit that's also got new upper control arms too. So much easier to just unbolt the arms and bolt up the new ones. The old ones don't get any stronger with age either.
Totally agree ....... Here is a kit I've used from Laurel Mountain Mustang. The kit I received had very good steel and was made here in North America (Mexico I think). Watch out for any kits that have Chinese steel. Ask the salesman before you buy where the parts are made. I've had Chinese bolts on the upper control arms twist off like butter 20 ft lbs before full torque. Do not buy Chinese kits. http://laurelmountainmustang.com/products/1968-1973-mustang-master-front-suspension-kit Full kit - $264
As long as your strut rods, sway bar and springs are good, the only other thing to buy is a set of new shocks. Plus whatever you decide to do about the front brake project. Oh.....and a front end alignment when you put all the new stuff in.