4AGE cylinder head plug removal

[Ivan141]

Has anyone ever removed the oil gallery plugs off a 16v 4AGE head?
My early bigport head is currently off for vapour blasting so I am expecting to get it back with blasting media contamination that could potentially ruin an engine really quickly if it's left in there.

There are 2 small hex grub screws that allow access to some oil channels but they seem to be rounding off when I try to remove them, so they are stuck in there good.
Hopefully someone here has experience with them and can give a few pointers.

As it is, I'm kind of thinking they will need a lot of heat, so perhaps buying new plugs and welding something to the old ones to get them out might be an option.

There's also a few big hex plugs along the spark plug valley, I'm not expecting those to be as impossible to remove but please let me know if you've dealt with these before to.

My idea to get the head clean include multiple solvent baths, pipe cleaners through the oil channels and any other bore, compressed air, and likely an ultrasonic bath. If that doesnt get everything out then it wasnt meant to be... but if the factory can clean up the casting sand, then I should be able to clean off any blasting media remnants too I figure.