C15 piston

[TSSWINDERBY]

Hi I am hoping to rebore a spare barrel before a Winter top end rebuild on my C15 , I need either a +40 or +60 piston the only ones I can find listed are Italian Gandini ones , does anyone have any experience of these pistons or know of any others that are available excluding JP which I  used once in the past unsuccessfully in a another application.
Many thanks Tom.