If you can't get another rail cheap or readily, then I would get a thread pitch gauge and see what pitch the schrader valve is (should be fairly common) and see if the hole can be chased with a tap to allow you to put the valve in. I would definately take the rail off and flush the crap out of it after you chase it. If there isn't enough there to make the valve fit, see if a machine type supply place can get a helicoil. That's the best that I thought of.

Shit is all apart. Typical...