Re: evinrude sportwin spark plugs
Either the J6C (best for low speed and trolling) or the J4C (best for high speed operation) will work fine. jnp. Gap either at .030".
You are correct about the RJ12C. It is a resistor plug for high temp air cooled motors like lawn mowers.
Do not trust any plug application chart. They lie. Trust the guys who made your outboard.