[Zeke]

I didn't read all the posts. if the cabinet is to be installed against the taller one just remove the left panel, cut your style and top and reinstall. AFA is not being symmetrical with the RS cabinet it is what it is (tell the wife). If the inside of the LS interior of the left cabinet means anything, throw a piece of thin veneer or paneling in there.

The proper way to do it is shave both left and right cabinets. Wife happy, you not so much with 2wice the work. Do remember that things expand with heat. Don't make it too tight or you will be sorry. Also that metal top will transfer heat. So will the sides. They are meant to be free standing and code says one inch of air space both sides plus the back.

You really are trying to put a 5 pound load in a 3 lb bag.

I'd build all new cabinets for each side with all the new cool features you might want there. Win, win.