I found these two miscuts, and although they don't shed any new light on the 1966 high series print configuration, they do help raise an interesting question. Both of these cards exhibit some marking which highlight that they are at the edge of the sheet.
539_edge.jpg
MC_24_D.jpg
There are 24 cards whose positions on the sheets are still unknown, and five must occupy an end position (since we know the cards at the end of both the Northrup & Mantilla rows). These cards are: 517, 523, 528, 531, 532, 538, 541, 549, 552, 553, 556, 566, 569, 570, 576, 582, 583, 586, 587, 590, 592, 595, 597, & 598.
Based on miscut information, we know that 517 is one of those five. We can eliminate 523, 532, 582, 583, 592, 595, 597, & 598 from consideration because we know there are cards to the right of those. That leaves 15 possible cards (528, 531, 538, 541, 549, 552, 553, 556, 566, 569, 570, 576, 586, 587, & 590) for the remaining four end positions.
If anyone has miscuts of these cards that show edge of sheet markings, please post!