This is a rather interesting video looking at the compression testing of a Perkins 4.248 tractor engine. This video is from Youtube user EngineerLikes Farming. Vintage Tractor Engineer follows this channel and likes many of the videos. We would recommend you subscribe too!
It shows the compression measurement at 24 bar (360psi).
One of the cylinders didn’t have any (or very little) compression due to inadjusted valves. You can hear the movement on the rocker arms that needed re-adjusting.
Cylinder number 4 had had a new liner and that was reading at 26 bar (380psi). The video doesn’t say if that cylinder had also had new rings, but it does demonstrate the difference.