While the stances of old have been for the most part abandoned in favor of Bruce Lee's principles of body movements and combat, as well as Carter Hargrave's own expertise in combat efficiency, you will not have to start over to benefit from Hargrave's system.
The system was made to build upon the knowledge you already posses if you are already a black belt. If you have no training that is ok too as all of the material is covered in depth from white belt to black belt in the training manual that lists all of the moves for each of your rank tests.
The second manual and third book authored by Carter Hargrave the Entrance to Secrets Japanese Kempo Training Manual. Available online at www.kempo.org