I hate to see a classic being broken up, but in this case that would make the most sense. A 270 in fair with rust condition is about $600 tops. A complete bolt would be at least $400 unless lucky. The one you need would be the easiest one to find however any .473 cartridge head bolt would work. There are no long, short, or medium Pre-64 bolts they are all the same but the bolt face. The parts have value, depending on the condition I would think at least $500. The barrel being the least desirable.