In order to buy piston rings (see my post about oil consumption), I've mailed to a specialist (DEVES) wich answered that they do not have them in stock, but they can do them, if I confirm dimensions !

"If you would like to give us groove specifications (groove depths) and
confirm that your piston is 84.50mm X1.75x1.75x3.00, we would be glad to
check if we could do them."

Can anyone confirm, and give me the groove depths ?