You might try a tight fitting hose on the bleeder and the other end submerged in a bottle with an inch or two of fluid. Open the bleeder and slowly depress the brake pedal, keep an eye on the fluid level in the reservoir. After pressing and releasing the pedal slowly a few times tighten the bleeder valve and see how the pedal feels. You may have to remove the caliper and have a time-sert installed at a machine shop to repair the bad threads.