Is the truck IRS or a solid axle? That makes a huge difference in where/how to mount everything. You need to also measure ready to run ride height from wheel nut to chassis bottom, full droop from bottom of the chassis to the wheel nut. You are going to want to know how much suspension travel you are wanting. This will make your starting point. Next, what is the trucks intended purpose; streetcar, drag race, dirt track, jumping, exc. next is finding out what else is attached to the rear suspension mount and what needs that mount; is the mount an attaching point to something else, is the mount also a locating point for other parts as well.
Once you have all this information, you can then begin to over come the problems faced with removing the suspension mount. The next problem your going to face is what off the shelf shock and spring is going to give you the travel your after and still have anti squat and control the spring. Then you can figure out how strong the cam arm needs to be, what angle the cam arm heeds to be, and where to attach the shock to the suspension arm and where you can attach the cam arm to the chassis. Lastly, how to attach everything.
My suspicion is your looking at one off parts. I have a guy near by that can design these parts on a computer then print them in PVC plastic on a 3D printer. I don’t know price that would cost. But I’m here to help. I’ve designed this suspension type a few times on full size vehicles. So please feel free to ask me any questions you might have
