Thanks for posting. Do the dimensions listed below match your old lock? If so, it's probably similar to our 90-274, save for those alignment nubs in the rear. We don't have an exact match for your face mount keeper, but either our 90-237 or 90-041 might work as substitutes. Both are compatible with the 90-274, so they might work for you as well. Please compare. You will almost certainly have to drill new holes in your sash with either of these keepers, so you should take a look at how much space you have and see which would be a better fit. If either could work, then it's simply a matter of preference. Note that if you do decide to go with either of these locks, just make sure you're careful when you drill. You don't want to cause any damage to the glass.
We unfortunately don't sell a lock with a 2-1/8" hole spacing, but we do sell a 2-1/16". See our 90-278. This is a very important dimension, so you need to be sure of it before you buy anything.
The keeper should just be screwed to the bottom of the top sash. To access the screws, you'll need to tilt in or fully remove the bottom sash.