Help finding the right crown

I have an Omega Seamaster from around 1960 - inherited. Case reference in 2849 SC-8. It is 18k gold. A non Omega replacement crown was put on by a jewelry store about a year ago as a temporary solution. From my research it looked like the original crown part for this watch was 42012 but when I purchased it, swapped the stem, and attempted to place it, it did not fit on the tube. I took a picture of the internals of the crowns - the new 42012- is on the right. I am guessing either 42012 fit a different tube diameter at the time or perhaps I just have the wrong part number. Any help in finding the Omega crown for this watch would be really appreciated.

Cheers!

Photos of the interior & exterior of the case would help, & of the watch movement, as well.

You may find this list useful;

Tubes usually 2 or 2.5 mm. All current gold crowns are plated. Vast majority of NOS crowns sold on eBay are just slightly older, but still plated

Finding a gold capped or gold filled 4 notch will be difficult. Might have to settle for the plated