If you set kused to 0 instead of KBLOCK in kdelete, then kinsert will not allocate a chunk on next yank.
When kused reach KBLOCK, it's the trigger to allocate next chunk, so initial state is kused set as KBLOCK.
If you rewrite kdelete as you did, you need rework buffer allocation in kinsert accordingly.
If you set kused to 0 instead of KBLOCK in kdelete, then kinsert will not allocate a chunk on next yank. When kused reach KBLOCK, it's the trigger to allocate next chunk, so initial state is kused set as KBLOCK. If you rewrite kdelete as you did, you need rework buffer allocation in kinsert accordingly.