I just did this in my 77 – a few times, don’t ask. All I did was jackstands under the rear framerails in front of the rear, then jack the axle housing up a bit, put jackstands under that. Unbolt rear from springs, then you are free to unbolt the springs. Front wheels sat on some homemade ramps that would support a peterbilt, but raising the front is probably unnecessary just for the rear.
Before I go under a car, I shake it pretty good and if it even thinks of moving I stop & do it again. I leave floor jacks snug in place too (not taking load off stands), just in case. God I miss having a lift. Next