Latching plate

If I'm understanding correctly, you need a new keeper for your mortise lock. Your mortise is a match for our 82-226, but this is compatible with a ton of different keepers; without seeing your original, I don't know which one to recommend.

With that in mind, you should start by looking at our 89-020, 89-021, and 89-021D. These are common pairings with your mortise, but you need to review their dimensions to confirm which one is the best fit for your door.