I'll echo 2door. Your chain stays (frame from cranks to rear axle)come back unparallel to the chain so ya gotta tweak it (the tensioner bracket) a little!
Kit chain is made from caramel & chewing gum.
I'm a big proponent of being a kit chain opponent! I have a track (bicycle) chain on my 2 stroke and it hasn't noticably stretched in 100ish miles. I'll buy a few front sprockets and face them off for 1/8" chain.
Feel free to pm me if your interested.