I did the math. Swift's 6" 504 lb spring will compress 42.8 mm on the front with 850 lb on it, that compares to my 63 mm compression on 342 lb springs. So, in the end including the taller stack ht KW tender spring you are getting, you would be sitting 1 mm higher than I am now, with your perch's in the same location as mine!!! Clearly I have about 1" more thread area I could go up. You are currently 1/4" higher than me and KW's recommended Max ride Ht is .6 in higher than I am now. So In theory you should not raise your car more than another .35". So, putting your new springs on the perch's where they currently sit will basically accomplish raising the car to the max recommended Ht. No need to do the math on the rear as the rear is more flexible, get the 6" for that too.