My bad, I was already happily forgotten that order number and was mixing individual pins to the equation.
It's definitely indicating pullups.
Anyway, I can only see that port pins are bidirectional and instructions are affecting the whole port.
Included schematics has 6k2 pullups for pins 14 and 15 but not for pins 12 and 13, all those pins are for port 4.
Pins 3, 16 and 17 are for port 0 and have 2k7 pullups but there are special connections.
Then AC/DC connector J1 and A/D Ohms connector J2 have no pullups and their counterparts have solid 2.5V references.
So pins 14 and 15 can be voted to have extra pullups and MK97400 is the correct order code.
Fast read of '78 databook couldn't see those order codes.
'81 databook has them on page III-84, page III-82 has emulation possibilities, page III-10 has old part numbers and external ROM version MK97401.
MK9750x has open drain port 5, so no good but their generic codes are also different, '82/'83 databook page VIII-11, page VIII-1 has more selections and MK97401 is missing.
'81 databook page III-99 has more numbering stuff.