The new Seafoam "Deep Creep" - works great like a Kroil as well.
I wondered, "why did he tap thru the clearance hole in the valve cover??." I know, you had other plans.
Anyhow, if anything has to be destroyed, don't ruin that head!! if you get tht cover off you should be able to grab that tap with something. Lube it up, go both ways slowly and easily.
Pretend your in Antarctica and you only get 1 chance to get this out; That's the frame of mind you want!
Try to grab the lower part of that tap (valve covers are cheap!!) turn it a smidge with oil, blast with air and repeat backwards. Keep blowing that hole lean!!
Good luck, should come out!
All our government does is distract us while they steal from us, misspend our tax $ and ruin our country