Spark Plug for 65cc Guzzino Hispania

I received this query from a member here who is struggling to work his way around the new forum…

I have been trying to source the recommended spark plug for my 1953 Spanish made 65cc Guzzino.
The owners manual offers two options; Marelli CW 225 DX or Maserati FM 225.
I cannot find an equivalent listed, and interestingly neither can the Green spark Plug Co.
I have no doubt that someone in the club has fond a suitable “modern” option. It is M8 thread; appears to be short reach with a copper washer and must NOT be suppressed. Help please.