It depends on how much total travel the strut has. Most racing struts only have a total of 1 1/2" of travel from fully extended to the snubber. If that's the case with your struts with 1 1/2" showing now your strut is "topped out" or close to it. It might be that someone has tried to raise the car from the ride height it was built for which is a difficult thing to do with a strut car. If there is no extension left in the struts with the car at it's desired ride height you will need to either lower the car, use a bigger tire or change the strut mount.
I would recommend using the hypercoil spring. They're a much better spring than the springs you linked to. They're a little more expensive but worth it. You can buy them from strange. I noticed the springs you linked to are priced each so double the price they have there.