brake pedal seal

[gab50]

I have a 50 pickup and have a CPP brake pedal hooked to a under floor dual power brake system. Where the pedal comes thru the floor the pedal shaft is about 3\16" x 1+". I want to make a sheet metal holder that would allow the seal to float in the holder as the arc of the arm moves around a bit. My question is what kind of material are you guys using for the seal. It needs to seal off to the engine comp but doesn't want to put enough friction on the pedal to impede the return stroke. I am thinking some kind of felt material. Just interested in what others have used.