Adjust the leg length so that the legs are the right height, and the same length.
No rifle will have a perfect fit within the bipod yoke. The rifle should sit within the yoke with some (intentional, even desired) rotation play. Shooting positions vary so much from lane to lane (side-hill slopes, etc) that the yoke will never be (perfectly) level. In a timed match, you will not have enough time to make any bipod sit level. And a tripod will work no better in this regard.
Only the rifle needs to be level. Install a bubble level on the rifle itself. Rotate the rifle within the yoke until the rifle is level.