Here is what I would do: remove the set screw and the lock bolt as Hoyt showed in the manual assembly. I would gently tap the complete oil pump out of the block so everything can be thoroughly cleaned. I would NOT drill out the studs from the outside of the block and take the chance of wrecking something. if you are patient and have all the lines off the pump and the lock bolt/jam nut off, it will come off. Its an easy process - just lube the thing and wiggle - it will come out.
