Seriously... I thought this was the whole purpose of a forum? To come forth with a problem and a theoretical solution then ask for opinions. At least that's what it used to be.
Heads are machined, ported, polished, modded, and even custom designed for race. So why is it so outlandish to think in theory, a drainage hole could be drilled as long as it doesn't of course intersect with an oil or coolant passage? It would simply go from the lowest measured point of the spark plug well to the outside edge of the head.
I thought of asking for a couple junk 5.4 heads to test drill all eight spark plug wells and see if any oil or coolant passages are hit. If they are, at least I can then see where they route and if a hole could be successfully drilled at a different angle that would serve the wanted result.
Our vehicles have ******, engineered to break away aluminum lower control arms so was it stupid of me to have mine gusseted with aircraft aluminum stock for increased strength? Mods are what some of us do. We don't do bolt-ons. We ponder, we theorize, we dream up solutions and then find a way to make them reality.
Scoff all you want. Maybe that's all you have going for you.