An engine in great condition should generally show only 5 to 10% leakage. An engine that’s still in pretty good condition may show up to 20% leakage. But more than 30% leakage indicates trouble.
especially if he's using rings with big gaps. i've got a pretty good size gap on top and bottom, i leaked 10% at 3hrs on the motor, and after about 30hrs, its down to 8%. the rings broke in and sealed up alil more over time. still have 240psi cranking compression across the cylinders, and i've put alot of nitrous thru it.