Diopos is right. But the latitude and longitude coordinates on the SH3/4 map are equal to the GE coordinates. It's just that the SH3/4 map is rectangular, and the GE grid is wrapped around a sphere (-oid). So nothing is keeping you from plotting your journey on it. The extreme end of
Land's End (or whatever Pacific Island) is where it is supposed to be. But your track wil look funny if you consider the distances over time and set speeds .