Problem with Mighty Demon 750

And the outer air bleeds are #50 drill bits. The inners are #51 drill bits.
Yes, the inners looked abnormally big. Sounds like you are pretty close to a good baseline now. When I saw the inners drilled out, and the rather largish air holes in the primary throttle blades, my reaction was 'uh-oh, what else has been changed'.....

With the blocks out, it would be a good time to check the power valve restrictions (the 2 holes in the power valve seat area) per the info supplied.