"IF" shot distribution was uniform throughout the pattern this would be very simple to calculate. Given the same choke percentage the 1 1/8oz load would have the same density as the 11/16oz one at 28% greater range. To have equal density the 11/16oz would have to make a 100% pattern at the range the 1 1/8oz made a 61% pattern.
It is of course not quite this simple as R'Man pointed out. There is even a bit of evidence that the pattern from a smaller bore might have more of a tendency to central thickening than the larger bore. "IF" this be true then the 100% .410 with 11/16oz could have a slightly greater range than the 61% 1 1/8oz on a perfectly centered shot, but the larger gun would have a better fringe area.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra