My 70 AAR had two springs.
My 74 has one spring attached to right side hinge only, left hinge falls freely.
My 71 has one spring atatched to right side hinge only, left hinge falls freely.
With only one spring, the right side (pass side) tends to want to twist up and be above the left side when closed.
However, if you adjust your truck latch to pull the lid down onto the trunk rubber seal, that should level the lid out when fully closed.
You can also move the truck lid on the hinges enough to level it out. Loosen both bolts on one side and move the lid up or down on the hinge, it will affect how the lid sets vertically. If you make the rear bolt higher than the front, it tilts the lid up in back. Do this on the side that is sagging and it will raise the rear of the lid on that side only and level out the lid. Then you will not be dependent on the latch pulling the lid down against the seal to level it, it will be level as it closes.
Good luck.