I think you will want to look up the dimensions of the MS F/A-18 and get the measurements of this landing gear set. You will need to consider not only how this will fit into the model but also how you are going to adjust the interior structure for mounting it up. This will also effect the weight as well.
I recommend getting a digital drawing program that comes with a ruler built in. Get a
blue print of the F/A-18 and scale it to the same size as the FT MS one. Now if you can get the measurements for this landing gear and draw them to spec, you will be able to line them up on the blueprint and get a rough idea of how much space you're going to need inside the fuselage and how much this may effect the CG. Taking the CG into account, you may have to place the landing gear differently to how they appear in the blueprint. Good luck!
