https://youtu.be/DdEnb3KN5lc?si=J6LAM84MsCMTNJN7
We have several members who have used the '87/88 FZR rim with our oem Speedo drives with no problems, myself included.
A quick check on the part numbers shows that your ABS speedo drive is the same part we use on our non ABS bikes. Are you sure you seated the speedo drive correctly?
[edit] Ok...I looked at your first video: https://www.youtube.com/watch?v=UT580fVXWjE
...and at the 12:18 mark you can see that the speedo drive in not correctly seated in the rim.
That accounts for the offset you found.
There may have been something different going on due to yours being ABS originally? Not sure?
I fitted a '87/'88 FZR-1000 "Genesis" front wheel to my 1990 using all the FJ parts.
FJ center-spacer, FJ bearings/seals, FJ collar, FJ Rotors, and FJ speedo-drive.
Everything lined up perfectly where it was supposed to.
Mine was pre-ABS though. :drinks: