It really depends on which Fett you're doing. Looking at the ESB photos, you'll notice that the armor is attached very close together. ROTJ Fett is a different gap, as well as the AOSW (SE Fett). If you're doing the SE or ROTJ Fett, just look at the respective museum exhibit photos in the gallery, resize the photo to scale it to your armor size, and measure the gaps from your monitor.