I have a 66 coupe and I was going to buy the mustangs plus kit with the 620 springs up front. I just don't know what to do about the rear. I would like to have the car sit level. I originally thought I would use 4 leaf mid eye but now am thinking about 4.5 mid eye. I am going to put 17x8 wheels if that matters. This is not a drag car just an occasional driver.