Slabby 750 fork stanchions can be "lengthened" by changing the rebound springs for 1100 slabby ones as they are half the length.
This allows the stanchion to pull up through the slider. The compression spring setup will now be too short but a longer tubular spacer at the top to bring the flat disc back to its original position solves this.
Had this setup in my race 750 and that lapped the isle of man in excess of 110mph