OH!
You must assume I drilled an ACTUAL ELIPSE! Well... let me tell ya...
I drilled these out by hand, just holding the thing down on the workbench and going for it.
When I say ellipse, what I mean is... I drilled out very small pilot holes to get started, then drilled them out with the 1/4" bit... THEN... while holding the little bugger firmly down to the bench with the drill bit running, I slowly lowered the drill down at an angle which ovalled out the holes a bit.
There's no exact science or math involved in the actual drilling process, so at this point the math is really more hypothetical than anything; although I DO very much appreciate you geeks putting your thinking caps on for this one! (I kid... I kid...)
At this point I think the math has gotten me close enough to what I am looking for, and now I just need to get the bike running and see how she works in real life and fine-tune it from there based on seat-of-the-pants feel, and whether or not it's completely deafening...
CHEERS!