If you compare the rear shoes to the fronts you will notice they are very much alike only the rears are slightly longer at the top.. My goofy neighbor took a set of rear shoes and cut off the "nose" of them and if i remember correctly he only had to drill one hole in each shoe to make the return springs work..
He used a 4 1/2 inch cutoff wheel
BTW,, 70-73 Datsun 510 rear shoes look slightly different, but are a direct replacement for the 410/411 rears and relatively cheap through Rockauto.com
Before the naysayers come on board with reasons it would never work... That car has had those "jerry-rigged" shoes for more than 2 years,,, It was the white 411 that drove over 2 hours ,, twice to Portland garage meets and again to Canby last June at an average speed of well over 70 mph...
:)
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