Your friend may have been talking about trying to rejuvinate an old ABC engine. Years ago it was found that some ABC pistons would grow slightly when given a heat treatment, increasing their size and giving back some compression seal after they were worn. As I recall, we heated them in the oven at 350 degrees for 5-8 hours, then cooled.

Engines with heat treated pistons, OS, in particular, did not grow to any appreciable amount. I seem to remember that Super Tigres did grow.