I think The gap is probably 3/32
That is awfully close. You will likely be hitting your scope upon recoil, which will flex the whole unit, including the hard guard. If I were you, I would look into slightly higher rings just to be safe.
As for getting a good cheek weld, I would really recommend an adjustable cheek rest. Getting a good eye position which is consistent is crucial for accuracy.
Good luck and welcome to the world of long range shooting. If you lived closer, I would invite you to my Long Range Tactical Rifles matches, but that would be quite a drive for just a club level match.