im taking rears, i miss understood so i think im good now. or where you taking about using your 82 front rear axle leafs for a shackle flip on mudwasp? if so does that push the leaf spring the same distance from the frame as the stock ones, so are the measurements or distances from the frame out the same?
i used the front spring mount from a 82 2wd as a shackle flip hanger it does not change the spring spacing,i went from a long box to a short box so the front spring hanger got moved forward and adds lift since it mounts in front of the bend of the frame, a up side to that swap is no need for a zero rate block to move the axle back to compensate for the shackle flip moving it forward.
the rear shackle hanger was also from that same 82 2wd just flipped upside down to use as the swing shackle for the sas, the front sas spring hanger is the one from any 73-87 chevy, since i used 52" long springs i needed to add support in front of the frame for the hangers to sit on where as standard 47" ones will not need that.
both the front and rear swing shackles i lengthened to make full use of all the arch in the front spring for more flex and it also helped the stock rear spring flex more, my shocks seem to limit my flex and at some point i will get even longer ones