Thanks.
I am a bit surprised. I thought it was fairly common practice to have the gland and lock nuts to be different sizes, since one is unlikely to have two the same wrenches in a set; not just for boats, but in general. Indeed, the eBay link you provide, which I had found, too, is for a set that are 2" and 1 7/8".
Catalina Direct sell the set that are both 1 7/8", but they also sell a set with 2" and 1 3/4": "These wrenches are for 1-3/4" and 2" nuts and fit many Catalinas using a 1" prop shaft and do not have the standard 1-7/8" nuts. To be certain they are correct for your boat, you may want to measure your stuffing box before ordering."
So, yes, I should re-measure, I guess.