HNT Gordon & Co. Classic Planemakers Australia
1000 Grit Water Stone
HNT Gordon recommend and sell Japanese waterstones. After regrinding your hollow ground bevel, your initial sharpening should be done on a 1000 grit stone shown in the photo.
Stone size 210 X 66 X 33 mm
The instruction leaflet Sharpening Process will come with the stone and details the full procedure for sharpening your blade.