Any society may be converted and licensed as a mutual or stock life insurance company by compliance with all the requirements of the general insurance laws pertaining to such life insurers. A plan of conversion shall be prepared in writing by the board of directors setting forth in full the terms and conditions of conversion. The affirmative vote of two-thirds of all members of the supreme governing body at a regular or special meeting shall be necessary for the approval of such plan. No such conversion shall take effect unless and until approved by the superintendent who may give such approval if he finds that the proposed change is in conformity with the requirements of law and not prejudicial to the certificateholders of the society.