You dont say what make engine but presumably a Johnson
The plugs listed in the parts catalogue are Champion QL82C
You may not find an exact equivalent in other brands
The Q indicates that it is inductively suppressed. If you do try any other makes avoid resistor plugs which you may find listed as equivalents. I found Autolite 422 listed as an equivalent but it is a resistor plug. I would not try it
I would expect Champion QL77JC4 to be suitable
Where NGK plugs are the most common ( most of the world except USA) I would try BZ7HS-10, but not BR7HS-10
