Should I use old style copper or platinum spark plugs in a truck that came with copper plugs

You may be better off sticking with the OEM plugs. Good news is that the plugs are easy to change on your engine.

Platinum and Iridium tips are much harder and do not erode near as much over time as copper/iron does, but is only a benefit if both tips are platinum or iridium. Because they are much harder, they are made with a finer point on the center tip.

A finer point allows a more concentrated corona to build up and will arc at a lower voltage across a given gap. This is why the specified gap for these plugs is usually larger so that it builds up more voltage before arcing.

Usually the double tipped plugs come pre-gapped and it is not recommended that you make any adjustments as the tips are very brittle. Anyway, the gap recommended by Ford for your vehicle is for the copper/iron plug. A double platinum or iridium/platinum plug will arc at a lower voltage and that could cause lower performance.

You could increase the gap to match the performance, but how much. I don’t have the charts and graphs or formulas that would give the optimum gap for your engine if you use a double platinum or iridium/platinum plug. You or your mechanic could make a guess, but if you’re wrong, you lose.