Lets skip the questions about why I want to do this, but I would like to run my front brake cable through my headset. This is an older race frame with a 1 inch headset. Most headsets built for this are BMX and I can't seem to find a 1 inch one. So I want to know if anyone knows of any parts that would work for me? Also is there a way to jerry rig the "AheadSet Hollow Cap and Bolt 1 1/8 Threadless Freestyle" to make it fit?
You're looking for a Potts Mod which allows you to route the front brake cable down through the fork's steerer and out to the front brake caliper.
This will allow the front fork/wheel/bars to do a complete rotation without binding on cables.
A Potts Mod does not work for a back brake - for that you require a detangler or to fit coaster brakes, aka back-pedal brakes.