hotchkis leaf springs sitting too low :(

I just installed the new hotchkis leaf springs on my 67 barracuda and the car sits even lower then it sat on the tired old springs. I re-used the front leaf spring hangers (to avoid it even sitting lower) now my 255/60 R15's rub on the wheel well lips when I go over a bump. Any suggestions on how to raise the rear by 1/2 - 3/4 of an inch?

What is the backspacing on those rims?

The Hotchkis springs are not factory replacement springs. They are made for handling with a lower center of gravity (lower).