[Goatracer1]

If rebuilding a 389 with standard bore cylinders who makes a good piston ring that will seat quickly.

[25stevem]

Total seal does.

But quick brake in and good sealing are a matter of other things these days then just the piston rings.

First off if your going to reuse pistons you should not have more then .004” ring groove clearance for the two top compression rings.

Next comes the bore finish.

If it’s a fresh honed bore it should be final honed with a Plateau hone.

With todays Moly face rings since they are pre-lapped at manufacturer, once fired up and the gotten up to normal operating temp the rings will then be seated already.