Oh i ended up using 4 laser levels to create a datum line to use as a referance for the lower frame rails / body to ground. 5 if you include the one for the center of the car.
I used pointed fishing sinkers taped to the frame measure points to make marks on the floor for the frame x measurments. it took me like a month on and off to set it up before welding. I was happy when i bought it to the body shop down the road and at most i was 1/16th off in any direction.