New steering cable annoyance

I decided to install the 98+ helm and cable in my '93 rather than buy the OEM $320 cable or the $190 aftermarket cable which nobody seemed to know what was different with the aftermarket cable. Besides being 6" too long the '98+ cable has a 5/16" hole on the rudder end where as my original had a 3/8" hole with a 3/8" bolt shoulder with threads reduced to 5/16 mounting it to the rudder arm.

Do I stick a 5/16" bolt in it or do I drill the SS steering cable end out to a 3/8" and weaken it that much more?
My next question is and I failed to make note of it when I took it apart, I'm guessing the purpose of the reducer bolt was to prevent over tightening? So how tight shouldni get it?