I agree with BBshark in that you'll have to make an educated guess where the c/g is. I've got a '93 rear suspension under my '51 Chevy pickup. Because it's a street rod and not my track car I was a bit more casual about getting the c/g location absolutely correct. I just set the truck at the ride height that I wanted, and then fabricated some frame brackets so that the trailing arms would have a slight incline (like in the picture) for some amount of anti-squat at that ride height.