So, I was trying to finish the plumbing before I started with the engine compartment wiring, and I needed a port for a barbed hose fitting to connect from the intake manifold to the heater. So I located a plug that wasn't being used for anything else, and proceeded to attempt to remove it.
IMAG1261 by Rick Paul, on Flickr
All the other plugs that I needed to remove came out with a minor fight, but they came out clean, no problem. The one that is circled in red in the photo was another story. Would not budge using a 5/16" allen wrench, so I scraped off any sealer that was around the edges of the threads, and saturated it with PB Blaster, and left it overnight. Applied some more today, and figured I'd get a 5/16" socket with an allen wrench, (not sure what they are called), so that I could get more leverage. Mounted it in a breaker bar, and proceeded to try to loosen it. All I managed to do was to screw up the allen socket in the plug, so that the wrench is useless at this point.
So now I need to figure what I can do to remove this buggered up plug. Do I need to drill through, and use an easy out, or...?
All suggestions will help. I'm in unknown territory.

Thanks