I certainly cannot offer any advice related to the Malossi barrel. I did do a little research for you. I checked the online parts manual for mc16 and it looks like the pistons all have 2 rings. So your single ring piston is likely from another bike or aftermarket. Maybe even from an RS250. Maybe someone smarter than me knows different. A few photos of subject parts and model year of bike or serial numbers might help.

There does appear to be several used mc16 cylinders for sale on ebay...looked in Italy and Australia, not US versions of ebay. All seem a bit rough. I did see one on yahoo auctions in Japan that looked a bit promising. It has piston too, but no rings. You can look at link below. Your budget may dictate decision on it.

https://page.auctions.yahoo.co.jp/jp/auction/x1113812954

Having just had a cylinder replated, I would say I would not do it again. For the total time and money I spent I could have had a new one delivered sooner at about same cost.

As for the full blown Tyga 300 kit, I have it on my bike. The failures I've had were not tied to the kit...siezed once due to lack of 2T oil and second time due to broken float valve needle. I love the characteristics of the kit but it's not for everyone. I also run it hard without mercy, but now I will be using it less as I have a new track bike.


Regards,
Eric