after driving for maybe ten miles brake pedal got hard and lost any free pedal play 2-3 inches normally , let sit over night and free play returned , brakes unseized I'm guessing plugged master ??

Check relief port in M/C is open. Remove filler cap and insert fine wire in smallest hole. I am assuming piston returns properly when you release the pedal.This activity you can see in the M/C when you shine a torch inside and with a helper to push the pedal slowly. You can also remove the fluid with a medical shringe while you are there and fill with new fluid. Use paper towel inside the M/C to mop up the dirt inside.
Dont push pedal while you clean the M/C out.

Another cause is the rubber cups in the master cylinder have swollen and are now blocking the relief port (small hole). If this is the case a rebuild is required. These rubbers seal on the edge and if this is damaged they no longer work.
Tony

While the above advice is right on, but in order to avoid all that trouble cleaning the MC up, you may try just driving it once a day and for less than 10 miles. Just saying.

Best,

Charlie

ty tyvm , my thoughts also , it has a rebuilt mc

Adjust master cylinder push rod etcentic as per shop manual demensions.

thanks chev nut ill have to find a shop repair manual