you could always try a pair of s10 cups, the springs are just about the same diameter, so maybe you might be lucky and have our cups fit right in to the frame of the 53. if not you could allways cut off the studs that hold the cups in place and let them free float, or weld in new bolts in different locations.
since the back is leaves, you would have to make a custom weld in four link.. or you again could do the same thing some guys on here do.. remove a leaf to weakin the leaves there now, and then add a 4" block to the car would hopfully layout.