Chuck, did you consider cutting blunting the tip of the jack, so that the downslope side of the housing is 90 degrees to the side of the Valley? That's common practice. The idea is that the jack will not act as a wedge. Imagine some thrust down the jack, and how it might want to pop the face off the valley. If you have the "red book", read the last paragraph on page 87, which explains it better than I can.

It's not difficult to cut these. On the Valley, it's easier to make a plumb cut than to undercut. And on the jack, once you've made the main cut like you already have, all you need to do is set the saw to 90, and set the base on the face you just created when you made the main cut, and nip off the corner.

I'm sure Mike will be along with a nifty picture illustrating this momentarily.