well you can do some basic engineering calcs yourself. Although it has withstood the test of time from a snow load perspective I would not put any type of dwelling on a 30' span from what you have stated are beam sizes.

Building codes here in canuckistan state a structue needs to comply to engineering rules. New or used building!

When in doubt buy local....find someone to cut you a frame out west based upon a traditional design. By the time you are done with this project, hauling, erecting and engineering you may just be better off starting from scratch!