Anything is rebuildable, but some aren't worth it. The problem with being in a fire is electrical and air components are almost for sure junk. Is that one all air operated or electric? If air it may be rebuildable with some new hose, valves, etc. Electrical can also be rebuildable but to me the wiring would take more work to rebuild. Also like mentioned depending on the heat temp of the fire some of the parts may be weakened. No real way to tell either until a part breaks under load. I'd take a guess at what it weighs and offer scrap value and dig into it to see if it is rebuildable or not. If not you're just out some time and gas money to take it to scrap yard.