David,

If you would like to get a visual of what kind of yield to expect. Then the following may help. If the Crotch is 6' high then the diameter you need is going to be at 3' high. That is due to the flair of the base and the crotch. So being optimistic lets say it is 17". So get a piece of cardboard and draw a 17" diameter circle. Then draw an 11-12" diameter circle inside of that. That is to allow for the sapwood. Which is likely to be buggy. Since that is why the woodpeckers are working on it. Then a draw a 4" diameter circle in the center. The four inch center will represent the early wood or pith and is not stable enough for furniture. Now you can start drawing slices of at least 1-1/8" across the set of circles. Anything outside the 4" circle but inside the 12" circle can be expected to be good usable heartwood. I hope that makes some sense. But keep in mind that this is a rough estimate.

James