If you need to leave an indication of 0 at the same rotation point then test for 0 and if so transfer that to the result else subtract the indication from 360 and store the result.
Yeah... that's almost how I ended up doing it.
Attached is the code I downloaded into the MicroLogix 1100... that lowered the scan time back down to what it was before, as well. The encoder we usually use is the Koyo TRD-NA360NWD from Automation Direct, by the way.