to have the spring captive and have the same ride height you will either have to get the strut tubes cut down to suit shorter shocks or run really soft springs, the first option being the better one

or if you dont want to do that you could just put some captive springs in for road worthy then put the king springs back in and just wire the spring in to keep it captive

any lowered spring that you buy that will be captive will make the car sit higher
so to do it properly you need to shorten the shocks