No, there are no chinese knock off engines the same size as the 90/110. The most chinese knock offs are based on the z50/atc70 sized engine. Once you get the top end off, then you have to check what kind of play is in the connecting rod on the crank. If there is too much play, then you will have to tear the engine apart for a total rebuild or that new top end won't last long.
Nicholson 500x (Project)
Nicholson 185s
Nicholson 110 (That takes an atc70 tank)
Ascott 500 head/350x (Project)
Homebuilt Racer Chromoly Suspension 110 (Ragin Runt)
PK Racing Suspension 70
A+ Inc Suspension 70
AWS Aluminum 90 frame
Hi Performance ATC Suspension frame rd350
Hi Performance ATC Suspension frame 90