Re: 1974 70hp evinrude steering
If you are at the end of the trim tab adjustment and it still is hard, you will have to live with it as normal. High mounting, or power trimmed out, will make it worse. The torque produced by rotating parts is what is causing it. Actually, a 70 hp usually isn't that objectionable. The higher the horsepower, the worse it gets.
You also might consider changing to non-feedback steering. That won't make it easier to turn, but it will lock at wherever it is when you stop turning the wheel so you won't have to develop Pop-eye arms to hold it there.