You're right, my worst experiences with platinum plug fouling were with Ford V8's also....I think they just tend to run too rich and sooty than some others, that's the common pattern with Ford carbs and Early TBI's, to wander to the rich side as they age.
I usually always stick to what the factory uses, I gave up long ago trying to see any tangible improvement from a spark plug change (other than worn out ones).
But if for some reason the OE plugs aren't readily available, I never hesitate to use NGK or Denso in their place. They make a really high quality plug.
I almost tried the Rapidfires in my Impala SS, but decided after replacing the coil, wires, distributor, and timing chain, (what a PITA, good thing it lasts 100,000 miles) that I didn't want to have to go back through it if I didn't like those plugs. I liked how it ran with the OE Delco plats, so I just stayed with what works.