Hello
see Amazon for Ryobi reconditioned chainsaw at 99 $, search in this forum a person with Ryobi chainsaw, have, this engine have converted here in a topic but I cant find the topic or my memory is falling.
This is a two ring engine .
Make a search in this forum a person converted it I saw.
May be it help you in your election, if you must disasemble, change bearings etc, carburetor, you spend near the 99$ and have an old saw engine , old carburetor.
Only my point of view.
I am also converted a Poulan 25 cc new and a Homelite 38 chainsaw bought used.
Also see garbage can in Walmart etc, I found two chainsaw chinese 40 cc brand BKS in a local mart , at 80 U$s each, new inside.
Happy landings
Jose