I/O (Sterndrive) Conversion to Outboards

[flashback]

Way I see it, your bolt threads will be coated with putty, may as well just run the nuts up and call it good. I've mostly experienced galling when removing the nuts not so much on installation.
I also think you may want to put a spacer type border, a tad less thick than the spacers, around the big access holes so the putty doesn't get squeegeed out too much.