mancini or jeggs leaf spring xhd 340duster

I am converting my 1971 duster from 6 cyl. I have a 340/727\ 8 3/4 rear. This is a street performance car . Im not sure which leafs to go with. Has anyone had experience with Mancini XHD spring? or Jeggs? they are both under $250 a pair I like the price not sure if they are any good? Thanks for your input.