I have made up an inboard suspension system for my car and one of the most important things to remember, aparentally, is that the angle from the pushrod to the rocker be as close to minus 90 degrees as possible. Also the angle from the rocker to the coilover be as close to 90 degrees as possible. Changing the ratio of lengths from the center of the rocker to the shock and to the pushrod with alter the load of the spring rates. With Honda 600 motorcycle coilovers with 800 lb. springs, I used a ratio of 7-4 and it seems to work. Ride heights can be adjusted with the pushrod lengths.
I have only put in 2 1/2 months of study into this and about 15 different mockups but i think i got it right.
But then again, WHAT DO I KNOW?????????????????????
P.S. Don't be disallusioned that you have to use a rocker that you may have found from a bike, MAKE YOUR OWN.....................