Leak Down Test On My New 418 Need Help?

Unfortunately, the parts list is too small to read the details and the piston line says 'with rings' so that tells us nothing except that the rings are probably circular.

The questions on the hone finish and rings have a lot to do with how well and quickly the rings will seat. For example, if the rings are chrome, then they may never seat very well, or will take a long time.

The questions on how the break-in was done have to do with the ring seating process. After 150 miles, IF you drove it a variety of RPM's, got it heated up every time, and gradually increased the loading to WOT or near WOT in that time, AND the hone finish was appropriate, then any ring (besides maybe chromes) should be well seated. Plain iron are not all that hard to seat properly.

The questions on gaps are similar: was it done right at the shop?

The other possibilities could be issues too... it is the oil on the back that is pointing to the ring situation, IMHO.

If you re-do the leakdown tests, you might want to make sure each piston is on an up-stroke when tested to simulate the rings being pushed downward by combustion pressure. And if the pressure is going past the rings, you may be able to hear it leaking into the crankcase.