piston resizing

[Dan Timberlake]

Originally Posted by Mike Pearson

They are for a 4.075 bore now. I would like to go down to 4.065 if possible. That would be .005 off the radius.

Piston skirts are usually not cylindrical. Some times they are some combination of tapered, cam ground, barrel shaped.
I wonder if JE can resize them.
https://www.jepistons.com/Catalogs/Automotive/NHRA.aspx

As others said, the ring grooves may need deepening. I don't think that can be done without the ring seal suffering,