Joseph Corlett often helps with sink questions. He has cut granite counters on site so if the sink is bigger than the present counter, it should be able to be cut to fit the new sink. Hopefully he will stop by to say whether he thinks this can be done in your case.

Here is a sample of his work:

https://www.houzz.com/discussions/4696057/kohler-apron-sink-rod-repair

Can you tell us a little more why you are unhappy with your copper sink? A properly made copper sink is supposed to be pretty much maintenance and hassle free. But there are a whole bunch of mistakes that can be made by the manufacturer. The most common mistake would be their attempt to put any type of coating or pre-finish on the copper. That's bound to strip of eventually. Another mistake would be hammering the sink, which can often leave uneven surfaces that won't drain properly (this can be done correctly, but many times it isn't).

Can you maybe post a photo?

It pretty much needs daily cleaning to keep it looking nice and nothing can be left in the sink. It’s just higher maintenance than I would prefer. I also I want to transition from a split sink to a single basin sink.

There are some options for getting a custom sized sink on this thread

https://www.houzz.com/discussions/5823603/need-help-locating-large-sink-basin-43-l-x-22-w-or-alternative

I wouldn’t put in a sink that resulted in such a deep negative reveal - the possibility of hidden gunk is not attractive, especially if this ends up being a rental

A half inch negative reveal is pushing it, but doable. I can pull the old and strap in the new in about 4 hours, plumbing included, but I'm pretty good at it.

You can always install a top mount/ drop in sink.

Joe, I was waiting for that! :-)

LOL!!!

I realize that undermounts are more popular these days, and that they do have advantages that shouldn't be dismissed. But a topmount can absolutely make sense.

We thought about this for a good while, when ordering our sink, and in the end we felt that a topmount was a better fit for our specific situation. And I still feel we made the right decision:

I just saw this photo! Glad you are liking the sink we made for you!

Honestly, having learned about your sinks was one of the best things that Houzz ever did for us. Before that, I had no idea how important it is to have a well-designed sink that is both pretty and functional. I realize that custom sinks are, by definition, more expensive. And so not everybody will be installing them in their kitchens. But in an ideal world, everybody should install one of your sinks.

We use it every day for multiple meals, and it makes things so much easier and clean-up is such a breeze. Love the integrated drain board, too. It gets a ton of use.

I have been doing a survey regarding saved time. Is there any way you can estimate the time saved per week, month?

It's really hard to quantify, as the workflow looks so different now. And I probably also use the kitchen more intensively, now that it is so much more efficient to use. It's not all thanks to the workstation sink. But that plays a really big factor. A lot of our design decisions were made after we decided on the sink.

If I had to make a guess, it saves maybe 5 minutes every morning, when I am preparing breakfast and take-out lunch for the kids. And it saves 10 minutes for your average weekday dinner. But there are big error bars on these estimates. And the numbers don't do it full justice, because it doesn't reflect just how much less stressful it as to get food ready while the kids are hovering all around me.

Having a central workstation where I can do all my prep and clean up in one go goes a long way towards cooking and cleaning up efficiently.

I usually serve the food to the family and then go back to the kitchen to quickly clean up before joining everybody for their dinner. Most days, it takes me about a minute to have the kitchen back in presentable shape. Me or my wife will clean more in-depth after the meal. But it's nice that the bulk of the clutter and waste can be put away so quickly.

Also, the integrated drain board gets used extensively in this family. It's a huge time saver that I can set things out there and have them accumulate a little bit before I need to dry them and/or put them away.