Engine Swap Help

[Puppet Pal Saul]

Hey guys. New to the forums here. I'm hoping for some advice on an engine swap. My uncle gave me an old 2007 Keeway Matrix 50 2stroke because he never put oil in it and blew up the motor- only 5000 miles on it. It's got the e40qmb in it. I really don't feel like getting my hands dirty because I won't have it in my own garage. So, is there a place where I can just buy a new motor and swap them out? I've been reading a little bit and what about replacing it with a JOG90, would that work too- depending on what size case I have? Just hoping for some general help on getting a new engine in there. Thanks!