offset shakles vs. kit

I am now a bit nervous about moving the rear springs on a '75 duster with a kit after reading many of the posts here. My skill level with a welder/fabricator ( I have the kit) is 0 and I am very new to this stuff.

I have seen offset shakle kits that seem do the same. I cannot see how the bent shackles pieces change the location of the pivot end. Lastly, are they same to use ?

Way behine on the build and in too much pain to acomplish anything at the moment...

Grassy