Early Silver Shadows have a master cylinder to provide brake pedal feel.  This master cylinder has a larger 3/4" bore than the original which is 5/8".  This improves the pedal feel.  This master cylinder is a direct replacement for the original.

Don't bother  rebuilding your stock unit when a brand new one is $60.

Early SY Master Cylinder

SKU: BTW125
$60.00Price