The person I asked for advice, and who provided it, is Stephen Fox. It was via private email exchange for which I am grateful, and I do not wish to misquote him here. I can tell you this: the modification made an unusable instrument usable, and he was right on the money with his advice.
We can theorize all we want about what happened to my instrument, thought I did not come here to argue or second guess the modifications I made. Sometimes theory is theory, and I needed action.
The bottom line is: I needed to get it into a working condition quickly, and there was nobody around to do the work. It didn't play in pitch, and now it does. Period. I've fitted various mouthpieces with different volumes before I made the changes, and like I said, it still did not bring the 2End octave up to pitch. The difference was close to 0. I did not make the decision to modify the bore carelessly.
Again, I am looking forward to your feedback on your taragot, once you receive it!
George