It sounds like the 82-244 isn't the right part for the job. I'd be happy to look into this further, but we'll need to see the original. A difference between 7/8" width and a 5/8" width for that faceplate is quite large, so I think we're dealing with something altogether very different. Seeing a photo of the old lock and the new lock side by side would be the most helpful. Thank you!
Thanks for verifying, Eddie. Unfortunately at this stage we don't sell anything that would fit that criteria. Allow me to explain the situation in more detail: the 82-244 is an assembly that uses the 82-218 mortise lock as a base, along with an additional face plate; the 82-218 is itself used for many many different doors and varies only by what kind of face plate it uses. The 82-244 is only one example of many variations, but at the end of the day they all use the same base. Or, to make it relevant to this case, they all have the same depth.
What that means is that if your depth is different, that means your assembly doesn't use the 82-218 as a base. What it actually uses, I have no idea. A photo really is the best place to start in this scenario, otherwise we have no means by which to research an alternative. Based on your description alone you have something very uncommon.