I tried looking up the pn's for you and the following was returned " The part PT9999, R91234 is no longer available. Contact your local John Deere dealer for other options"
Where R91234 is the ignitor (coil) and PT9999 is the spark plug clip/boot pieces to complete the assembly.
From Google search: "I HAVE BRAND NEW UNUSED AMT 600 IGNITOR/COILS. Direct replacement for John Deere R91234 and Kawasaki 21119-2071 LIMITED SUPPLY CALL OR EMAIL " https://thegatorguy.net/
If you ever determine an equivalent Kawasaki P/N or other, please consider posting as it appears others are looking for a solution.
Good luck.
Added in edit: One of the posts claimed the Kawaski PN is 21119-2115. I can not verify this is correct, but found a few places that list them. Example: https://www.m-and-d.com/KAW-21119-2115.html?id=LCaxehHN