Adam,
Jon is right about the holes not being the same. I did the same thing you are doing a couple years ago and ran into the same problem. I had the same problem when I went from Pinpoint to Minn Kota as well. We could not be so lucky?
It would nice for every mfg to conform to a foot print that would be industry standard.
They are several things you can do to coer up old holes..some silicone over the holes, grommets, some put a new t-motor mounting plate (like Jon mentioned)on there to cover the old holes up, or Frankie’s marine has a fiberglass repair guy that does excellent work for very reasonable rates. A friend of mine has his Ranger done this way and you cannot tell where those old holes were. I am considering swapping my kicker motor from one side of my boat to the other. I will have this gentleman repair the Panther bracket bolt holes when I do this. Have not fully decided yet?