If you look at a polar projection map, you can see that WBZ null is actually aimed at NW Africa, and the side of the major lobe, which is in excess of a non-directional 50 kw equivalent, is aimed right at northern Europe and Scandinavia.
Similarly, WWL with a lobe that pushes more power north, aims right at Europe.
Since neither 870 nor 1030 are European 9 kHz separation frequencies, the path for both stations is wide open.
1510 Boston used to make it into Ireland and the UK at night even at reduced power, I seem to recall reading back in the day.