@John ******
your original entry might have been on a tourist visa but the last Non-Imm type one is the Non-B that you got your employment extensions from. AND you're not going to get any non-O visa, all you're doing is canceling your current extension based on employment and then applying for a new extension based on retirement.
You are making it hard by moving between the time you stop working and want to get your retirement extension.
The sensible thing to do would be to cancel your employment extension at the office where you are and then immediately apply for a new yearly extension based on retirement. (It's issued the day you apply) THEN move to Korat, and file a new TM30, start doing 90 day reports etc