The doc that has the TMS1400 info also has some TMS1700 info. It says that there are 8 pages of 64 bytes, so the page address register and page buffer register are both 3 bits wide.
So I guess the first 1/2 of a page is in one column of bits, and the second 1/2 is in another column.
I just changed the # of pages in my conversion code, so it didn't account for that. I'll look at the circuitry above the ROM array and see if I can figure it out.