Hi chance:
Just an observation, there is nothing wrong with a good quality 48 inch level it has many good uses. The old timberframers used only solid wood levels of 30inches, stanley was one of the earliest to produce them, and can still be picked up and put in good order.
My advice from experience is to obtain a good quality brass plumb bob, and use it to plumb your frames. just hang it where ever you can and it will give you an unmistakably true vertical line that might be impossible using a level on a sawn or hewn wood surface.
NH
