I'm not sure I want to know why you're asking this....
HOWEVER, in the interest of science, and in the spirit of "measure twice, cut once"...
Note that the edge of the rim and the fork itself are NOT perpendicular in your area of concern. The closest distance from rim to fork crown is at the very front edge of the fork crown, so that's your critical point.
Looks to be right at 2 inches (~50mm) clearance, or slightly less, from rim to fork inside top...
Granted, after four years and 18,000 miles, the wind might have worn some of the thickness off of my SXP fork... YMMV