Belgian,
The P&C from an original EZ may fit. Bore and stroke are the same according to Mike Acres site. Can you get a part # for the 6-30? The numbers I have for the EZ is 55490 and a newer # 56182A
I have two EZs - the first one has the handle covered with the green coating and the top of the cylinder looked like yours - it had some scoring so I replaced it but you can have it it you think you can clean it up - I can send a photo, I think I still have your email address. On the second one, the fins on the cylinder are horizontal clear to the top but the two appear to be interchangeable. This cylinder also fits the 5-20 and maybe the 600D. The two part numbers may relate to the fin configuration.
I'll keep an eye out for one. Cheapchainsaw parts seller on Ebay has had a few of these.
Buzz was kind enough to sent me a free EZ cylinder that fit perfectly well with my 6-63 !!! It had quite some marks but it cleaned up pretty good so I could finish the saw. The orginal piston had a light scoring too with a stuck ring, but I was able to free it without damage.
I had quite some work to get the carb going, but she fired up soon after.
Then noticed the idle going up continuously, so it has an air leak, grrrrrrr. That's what caused the original scoring i guess.
Checked the seal on the clutch side, which looks like a bronze bushing....so, I decided to leave it there for the moment.
Thanks again, Buzz Sawyer