There is nothing needed using UCenter since you use a revo board.
Ucenter is only needed for CC3D as described in
Wiki page.
Even if you change something in UCenter into the small OP GPS the configuration is erased by the Revo or simply lost after some time when the capacitor is discharged. This small OP GPS do not have memory for config storage and in fact, cannot be used with a CC3D.
Prerequisites for a green GPS alarm is a number of sats used
above the value set (default 7) and also a PDOP
bellow the value set (default 3.5).
See this page, related to GPS setup using a Revo.