122" plus overhang will be 125" minimum, which will likely require a minimum slab of 126-127". If you can drop the width by about 5", that will greatly open up the number of stone choices you have as one slab. Ideally, I'd recommend not more than 115" of cabinet run so that you can likely get away with any slab that is 120" or longer. The slab choices drop off relatively quicky as you go bigger.

We needed about 123" and had to wait for a specific lot of slabs to be delivered that had sizes big enough. Also, some stones don't typically come in the larger sizes depending on the quarry and source. I would highly recommend no seam ob your island. You won't lose much by reducing the cabinet width by 5 inches or so.

You are already looking at stone- have you asked the stone yards what jumbo slabs they have? That’s where I would start. And yes, be open to a slight redesign of the island to reduce the length slightly.

My island counter is a shade over 124" and I don't have a seam and my slab wasn't marked as jumbo. I agree with Hallett that you should go to stone yards and take a look at the sizes of stones you like. I found some (that I didn't use) that were about 132" and not marked jumbo; jumbo slabs were bigger although most that I found were quartz if I recall correctly.

I'd avoid a seam if possible, especially if you want a stone with lots of movement. Some seams turn out nearly invisible (good fabricator, home owner involved in template process, or book-matched slabs); unfortunately we've also seen many posts here from folks unhappy with their seams.

Thank you!! There's hope for a seamless island then :-) Unfortunately, the cabinets are in and due to an unforeseen challenge during installation that required the addition of filler, the island is now the full 122"... Hindsight is 20/20. We are lucky that the island is just inside a 36" door feet from the driveway and there is good room to maneuver, so from that perspective, we are in good shape.

Also be sure to speak with your fabricator and contractor about proper support for the overhang. We have steel supports, which were planned and discussed by the cabinet maker, GC, and fabricator to make sure everyone was on the same page.