I still think you'll have problems with the weight swinging back and forth, and wild readings in general just do to the different G forces.

If you're just looking for a way of finding which way is down during level flight. Perhaps as an aid to setting the trim. I think it'll be a lot easier to use an accelerometer. It's not going to give an artificial horizon, but it can find which way is Up. It can also give other interesting info like the G force of a turn or the amount of turbulence.

There's a nice one at Parallax for pretty cheap. And it works with PULSIN, so no interrupts or quadrature encoders to deal with.

Memsic 2125 Dual-axis Accelerometer
http://www.parallax.com/detail.asp?product_id=28017

Understanding the Basics of an Accelerometer
http://www.parallax.com/html_pages/r...s/cat_acce.asp

HTH,