I am given a port and starboard option for the linkage, does this refer to the side of the boat that the linkage is on, or the side of the boat that the cable comes to the motor?

What mot r are we talking about?

I am referring to the steering linkage for a 1990 mercury classic forty. I believe that steering linkage would be the same for all motors. It is the arm that goes from the end of the steering cable to the motor.

Normally the tilt tube is set up for Starboard entry of the steering cable