What you're describing is virtually impossible. A 65 truck with a 6 cylinder will have a 230 or 250 engine, and a 216 starter (or any 6 volt) cannot be bolted onto that engine. If the ignition system is working properly, there's a piece of nichrome wire from the ignition switch to the coil that drops the running voltage to slightly over 9 volts when the charging system is producing 14V, to protect the points. The only time you'll see full battery voltage at the coil is while the starter is cranking.

Find a good Chevrolet service manual and read it before you start condemning stuff that's probably working right in the first place.
Jerry

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