Andreas,
I think I'll follow your setup w/ the 99 OEM Coils. I called up Bilstein ( I have a 2wd bilstein shocks and the 4wd bilstein are diffrent for the front , rear shocks are the same) and the said that the shocks has the same height and mounting, only diffrence is the valving where the 4wd is more firm.
Called my local TOYOTA Dealer and wanted 85-90 dollars per spring(about 380 for the set). Can you post the phone number for Jay Marks (Champion) Toyota where you got it for 220 for the whole set. I checked PP coils and they are 370 + shipping.