Help with ADXL345 to Tilt angle conversion to analog output

I would like to be able to use an ADXL345 board with I2C and take one of the Axis and display the Angle output. At the same time, I would like to create an analog voltage output corresponding or scaled to the Angle. Primarily I'm interested in measuring say -60 degrees to +60 degrees and scaling the analog out from 2.5 to 4.3 volts in that range. The angle the sensor will be tilted should never exceed that +/- 60 degree range.

To measure one tilt angle, you have to read two correctly oriented accelerometer axes.

Here is an introductory guide.