Livestock housing is often made of metal. What makes it functional is the ventilation you would add. If your comfortable with purchasing a new structure then cutting into it a lot of ventilation then sure, go for it. The insulated roof aids in reducing summer over heating but you'd also want side vents you can open in summer and close in winter. basically what you cut out attach back with hinges and install hardware cloth inside of new opening. You'd provide exit vents on the gables that would stay open year round.
It's a cost analysis. Cost of materials to build from scratch with time opposed to cost of structure with time to erect and modify. For me it would be better to build from scratch as that way it's built to suit the intended use. Framing only needs to be 2' on center and no reason not to use 2X3 with a half inch T11 style sheathing (quick to install and takes an exterior stain well for fast beautification and protection). You'd want bigger rafters for snow load of course or buy prefabed trusses. If the structure is surrounded by a skirting of hardware cloth laid parallel to ground to prevent predators digging in then it can stay as a dirt floor. Once you start thinking of building a large chicken coop on sauna tubes instead of a building your costs dramatically decline. No overhead doors, no floors needed, doesn't need actual windows just vents covered with wire, doesn't need insulation or framing to provide for insulation, etc.