This block fits in the lower channel of the header and will slide sideways to any position you require.
This block has a clearance notch on the top of it to fit under the wall bracket when the hinge will be mounted close to the wall.
Installation is easy. Remove the base plate of the hinge being mounted with header. Slide the block to the desired position, and drill a 3/16" (5mm) hole in the header from the bottom using the hole in the block as a guide.