Lift kit - Upgrade Question

[chevydeth]

I tried searching on here and google and I can't seem to find the answer. I have a 6" Pro Comp with the pro runner shocks/struts in the front/rear. I am thinking about upgrading my front struts/strut spacer with coil overs. I know there are a ton of brands out there. For simplicity purposes, say I would go with the pro comp 2.75 coil overs, would they fit with the strut spacer taken off? What fills the void space when the spacer is taken off? It says on pro comp's website it will lift up to 2.5". Thanks in advanced.