1: There will be no R160 G trains whatsoever unless there is a G/O.
2: The G's R68s are coming from the B line equipment pool. IDK what is going to fill in on the B.
3: The #1 reason for why 75 footers are not allowed in the East is because of sideswipe risk.
The curve off of the bridge on the Brooklyn side, the Myrtle avenue curves, and the sharp curve near cypress hills are all places where a 75 footer can sideswipe other cars and signals.