Mine is a little higher in the back as well so I use higher blocks in the front which levels it out. I have a 7000 and use the SUV style blocks that they sell. Since I have subframe connectors, the rear blocks will rest on the connectors where they meet the forward spring eye, the front will reach the flat part of the front subframe, just rear of the curved portion.
The lift is very stable. The reason I bought a 7000, is because I also use it on my 2017 Colorado, the frame is even longer on that, and it supports it just fine.
Another way to place the lifts is perpendicular to the frame (one lift for the rear and one lift for the front). When lifting the car will move to the side.
1967 Camaro: True RS, Tribute SS, 350 290 HP, Muncie M20 4 SP, 12 Bolt Posi