Roller chain for oversized sprockets can be considerably longer. Standard chain lengths sometimes do not fit. Electric Motorsport sells chain length up to 10 feet which is long enough for any chain drive. The chain size and length should match the drive and driven sprocket you are using. Remember to allow for some chain slack and any possible suspension travel. It is a lot easier to remove chain links then it is to add them so always allow for some extra links in your measurements.
Roller Chain #40 Price...$33
Roller Chain #50 120" price...$50