It can be measured with the clutch bolt and washer removed from the end of the crankshaft.
If you do not want to open up your engine to replace the crankshaft (appx $35), then sell your Hisun and buy a predator. Before you sell the Hisun and its gas tank you may want to see if the Hisun's tank can be used on the predator. You will then not have the gas cap issue that you see in the video. It should fit.
If I was in your situation I would just order a clone crankshaft and swap it out. But that's just me. Others have bought a new engine just to make the torque convertor install easier.