Insulation, Radiant and Vapor Barriers - Foam Insulation for old Grainery

We are planning on doing a lot of renovating in our old grainery to make it more usable. We are thinking of using the blown in foam insulation because the old tongue and groove siding is far from airtight. We like the looks of the old wood siding. Is the blow in foam insulation a good solution? I have heard it will not mold and strengthens walls. I understand it is more expensive, but maybe not if we do not have to reside the building, right? This building is from the early 1900's and instead of 2x4's, etc, it has logs and rough sawn lumber for the upright supports.