Hi Rich,
Nice lock! Something to consider. The lower leaf of the mainspring is very close to the edge of the lock and you have plenty of extra toe on the tumbler in front of the hook when the lock is at rest. If it was my lock, I would heat the bend of the mainspring bright red, place the bend on an anvil and hammer the bend a bit more closed. Then I would evenly heat most of the lower leaf to bright red and grab it with pliers just before the hook, and give it a gentle arc downward. Then makes sure it fits and the hook is not now short on the tumbler. Then heat treat. That will raise the lower leaf away from the edge of the lock plate and also likely enable the lower leaf to be straight when the lock is at half cock.
dave