When I got the bike the guy had rebuilt the botton end, had a rebore done and bought some 30 over pistons and rings. He latter sold off a lot of his spares and the new pistons were taken by mistake by someone else. I have only the rings which are still in the box and the old pistons in the engine (which are stamped +030 4L). The guy suggested I should buy new 30 overs but Im not sure what to do as this is my first project?You'll find a few re-brands of JCC pistons available, very good inexpensive replacements.
Re-bore should be .0045 larger than the new piston's skirts.