Just for the record, I'm running on about 6 hours of sleep in the last 72 hours, but do yourself a huge favor and go pick up the "U" bolt type rings (Sea Dog makes some inexpensive ones), when you go to install them, Measure to the middle and make a mark (I use dry erase markers), then simply measure out evenly and down from the moulding, I always make sure the boat is level then I can just make sure the eyes are "plumb"...
The rings you showed a picture of are not very strong because they pull sideways and tend to crack the gel.
Good luck...
GT