0.016" might better suit starting if a magneto is used.
Without any doubt my plug of choice, and thankfully I might have future proofed myself, but bizarrely enough, KLG FE70 (Smiths Industries) spark plugs, a good old, but long defunct British company, seem to be far more readily available in the USA than they are in England.Plenty of NOS KLG FE70 to be had.