You're in Tennessee? Have you met HoMeLessJoe?  Take the gun to him and have him take a look at it, he absolutely loves W&C Scott guns.
Have your machinist friend make you a new screw...more than likely he wont have the cutters to match the original thread size, just have him make a screw with standard threads close to the original pattern and re-tap the threads in the action. Just has to work...doesnt have to be perfect right?  If you were to have a screw made, fitted and finished that look as if it came with the gun from the factory...its going to cost you more than you paid for the gun.
Dustin