MA WTB stock 3/4 ton leaf spring shackles and shackle mounts

[gmc1971harwich]

I'm going from 38 inch tires to 255/79r16 all terrain which come out to 30 inch tires should be ok with clearance I would think how much would it be for the front and rear leaf spring mounts with shackles shipped to 02631 might be a week or 2 before I can buy them but nice to get a $ estimate to plan ahead. I plan to sell the old lift kit mounts after installing stock stuff. I think I should be able to reuse the leaf springs how do I measure them to make sure they will still work?