4 link triangulated rear suspensions

I want to change the leaf springs to a 4 link triangular suspension the kit I'm Interested in is made for a 67 I just want to make sure I don't have to make any magor modifications to install this kit
Your best bet is to call that manufacturer, provide them with measurements from your car, (frame rail width, axle centerline etc, assuming they don't have it already) amd see just how close their kit is. You're gonna have to measure anyway, may as well have those numbers to start with