Greg is pretty well on the mark, from what I have read, heard and done. "Clock position" probably had little or no bearing- 4:00 is no better than 8:00, or anywhere else; it just makes positioning the mic easier- distance of hole off the floor is about the same as height of the mic from the floor.
A hole big enough to allow you to store your basketball inside your kick drum is about the same as no reso head at all- a drummer behavior that always had me scratching my head, even when I was 12. What's up with THAT??
Perhaps the easiest and best way to make the hole is to heat a coffee can up with stove burner or hand-held propane torch, then push it through the head. Fast, easy, the hole is perfectly round, it even melts the edge of the hole so that the hole won't "travel."
I have never done a hole-size and/or location comparison, but that might be a fun and informative thing to do. I have not seen any done, but of course I could have missed several. Whoever did it would want to control variables- do things like use all the same equipment, mic's, drummer, room temp, changing only the hole size and location on the head. You could (probably should) record the drummer playing the kit to be same drum-less backing track, also playing the same drum solo, and kicking the bass drum alone, with each different hole configuration. Also run the kick only signal to a computer program that would show the frequency response/etc. (what is that thing called? Blanking right now...) With some good experimental technique, good writing, clear photographs, and organized style, this might be an opportunity to get an article published in a paper magazine, or at least an on-line zine or forum like this one. Without those things, it would be a mess.
