Strut Replacement 1990 JDM SW20 Turbo

Can someone help me with a couple of questions in regards to putting in some rear struts, I have a set of with lower King springs KTRL-11 and wonder if the stock strut inserts will be fine with the lower springs? And will this be OK on the front as well?
 
And the second option is a set of Cusco struts, But these look about 30mm shorter than standard. Would anyone know if this is because of the more rigid springs and the lower amount of travel will be around the same once the car is on the ground.