ring groove spacers?

[40 Deluxe]

I have a new set of Ross pistons with 3/32" ring grooves. Does anyone know if spacers are available to fit the narrower metric rings? They would need to be about .054" thick for a 3 3/8" piston.
Back in the day, pistons with worn grooves were repaired by machining the grooves oversize with a tool (made by Perfect Circle, if I remember) and installing a spacer, which worked well.

Thanks!