Looking at that rotor I bet your inner disc is well below minimum which was only .94 with a disc that started at 1.

New one piece disc for the small bearing spindle are just $55 Rock Auto.

New pin type caliper for the 70-72 B/E also pretty cheap at local auto store or RA.

I had to go through all this with a 70RR.

You just need to verify which spindle you have, but if the 10.98" rotor it should be the small bearing.