We got a drain assembly from Brizo that matched another sink brand's hole, but I don't know what to suggest in your case. Many people are abandoning the basket concept as far as some of the showroom sinks I have seen and going with purely disposal openings with a separate dishpan placed inside the sink if you want to fill with water. Fireclay can be a delicate material, so that's honestly not a bad idea to help protect the finish. You could get some sink bottom protectors with soft feet like this: https://www.bedbathandbeyond.com/store/product/oxo-good-grips-reg-sink-mat-in-grey/3339886?categoryId=14570

And then pair it with basins like this: https://www.amazon.com/SAMMART-2-4Gallon-Collapsible-Dishpan-Draining/dp/B07DCRL16M or this: https://www.bedbathandbeyond.com/store/product/prepworks-reg-collapsible-dish-pan/1042694892?brandId=2993

You can also contact the manufacturer of your sink directly and see what they say. We purchased a Whitehaus sink recently and were dismayed to find they didn't offer the drain mechanism with it which had to be rigged with tape since it was an odd configuration. So, you never know if these sink manufacturers are thinking ahead to the total installation or not, but it might be worth a try.

I called and they recommended the short one that I originally purchased with the sink. :/

Fire clay has issues with warping as they are fired. It’s probably not the standard sized baskets. It’s probably the sink opening is off enough that things just don’t quite fit. You’re going to have to sleuth *how* the hole is off to know what can work here.

I ordered a cone looking one. The hubbs thinks it will work. If it doesnt, we are going to call a plumber.

We have a 30" fireclay but have a disposal connected to it. I can post pics but not sure that'll help?

Sleuth the sink issue first. No plumber can fix a warped fire clay sink. That has to be exchanged out for a different one.

Oy.

The common denominator is the sink. Was it not inspected and tested before install?

We installed it ourselves. We tried out the initial basket and determined it was too small short. The hubbs did a quick dry fit with the long shank basket and thought it would work. Went to hook up the plumbing after countertops and pics above are what it looks like. ☹🤦‍♀️

Went back to the showroom and plumbing store. Brought my deep shank basket strainer to test on the display sink. Same problem. Went over to the plumbing side and found a different style of basket strainer and took that over to the display sink. It looks like it will work. I'm a bit miffed that the employees acted like we were crazy before seeing it ACTUALLY DOESNT FIT (the one they sold us). On the way home to hopefully install and get a working sink. 😅