There is a guide, it's a yellow line. Unless one of the a/c involved wasn't on the yellow line then the markings are wrong and there should be a warning as such (just like on the ATIS at LHR after a similar incident). In fairness if everyone stopped to get positive visual clearance ( from whom ?) every time a wide body passed another wide body on taxiways there'd be gridlock at JFK.
the yellow line is striped and if you are aligned with it you can be absolutely positive you WILL have a wingtip strike.
Virgin was already to the right of the line.
the yellow striped line marks the middle of the pad as measured from the edge of kilo to the edge of the pad (completely useless for pilots orientation).
a center line 40 ft from the edge of the pad would me much more useful and would have provided a wing tip separation of 40ft assuming both airplanes are lined up with their center lines.
just measure yourself:
https://orthos.dhses.ny.gov