M_Boats: M-17 FURLING HEADSAIL

Fellow sailors, I am considering a furling headsail system for my M-17 "Little Breeze". I was looking at the "Harken" small boat setups but one thing is not quite clear to me will I need to replace my existing jib or find someway to seize it to the forestay? Additionally, I enjoy flying my 180 Drifter in light winds, will this system make that impossible unless I install dual forestays. Any help would be appreciated. When I bought the boat it came with a spinaker which I have never used and never will, any idea how much I should ask for it on Craigslist? Regards...Arnold Sharpe...M-17 #265..."LITTLE BREEZE"