It looks like a small motorbike/Goped motor.
I've looked at one once and decided it's probably too heavy for air applications.
The best conversions come out of chainsaws and to a lesser extent weedies/blowers.
I have a 37cc from a chainsaw and a 52cc from a large brushcuter, both new and in the process of being cut/converted.
The 37cc looks like a powerful engine with huge transfer ports (2 x 2) and a generous inlet and exhaust ports.
I think it will be significantly more powerful than the Homelite 33cc chainsaw engine I converted which is very nice. Just need the time...