That makes little sense, you already have a spring (leaf spring) which is roughly the right spring rate (this provides both ride and roll requirements), so you then go and add another spring, for what purpose? Was the leaf spring too soft? or is it just the wank factor of having coilovers. These will not provide any better rear end control, you are still constrained to the inherent "deficiencies" found with leaf spring and still not the tunability provided by a 3/4/5 link system.