Broken K frame bolt 74 Swinger

Not knowing your skill level, I'd be tempted to use a cutting torch with a small tip to blow a hole through the old bolt. That might even break the threads loose in the process and allow you to use an easy-out. From what I can see in the photo, the threads at this point should still work ok. You won't know for sure until you get the broken part out and torque down a new bolt.