I think that if you are willing to spend $415 dollars on a motor you are better off buying a Morini.
Either way you are going to spend a great deal of extra time and money making it work. After you custom build your motor mounts and all the other custom pieces you will require (extra wide crankset etc.) you will still have to upgrade the rest of the bike to handle the increase in hp.
Also, The motor you are quoting is of the type that makes its power at a very high rpm so you will have to figure out some method of gearing that down to get it in a usable range.
Another point, I don't see anything that looks like a clutch.
I saw whole pocketbikes starting around $200. you could use the engine,chain,sprocket?,gas tank, and its a pullstart so it would have a centrifugal clutch on the engine. or you could just get a regular bike engine kit for $109 with free shipping.