A Quorum of /70/ Apostles when united are Equal in authority to the Quorum of the Twelve Apostles.
The Twelve Apostles or traveling Council are to be special witnesses of the name of Christ in all the world. They are Equal in authority in there decissions to the Presidency of the Church. They are to preside in all the world whare the three first Presidency are not.
The three first Presidency Preside over the whole Church & administer in all the ordinances of the Church which Consists of a Presidet & his two Councellors.
The President of the Church holds the keys of the sealing powers & his Council act in Concert with him [in] all things.
Should the Presidency die The Twelve Could organize another Presidency & should the Presidency & Twelve all be slain the Seventies being Equal in power & Authority to the Twelve or first Presidency Could organize both Quorums.
A Bishop has two Councellors. There is no difference in the authority of his Councillors. The 2d has as much authority as the first. A Bishop should have his Councilers with him on the trial of a case in order to make it Legal as it takes three to make a Quorum.
The High Priest Could organize the Church in all its parts if all other Authorities were dead for they have the Melchezedek Priesthood out of which grow all of the Higher offices of the Church.
An Apostle is the highest office in the Church & kingdom of God. Joseph Smith was a Prophet Seer & Revelator before he was baptized or ordained to the Aaronic Priesthood or had any Authority to administer one of the ordinances of the house of the Lord. He was afterwords ordained to the Aaronic Priesthood then to the Melchezedek Priesthood & Apostleship which is the highest office in the Church & kingdom of God on Earth. When a man is ordained to the Apostleship & keys thereoff if he dies in faith He will hold those keys to all Eternity. All the Prophets Patriarchs & Apostles who ever did or ever will hold the keys of the Apostleship if faithful unto death will hold them forever.
Presidet Young was an Elder when he was ordained to be one of the Twelve Apostles. Some asked the Question how He could officiate as an High Priest not having previously been ordained a High Priest. Joseph Said the Apostleship covered all the offices of the High Priesthood the same as a private member ordained a High Priest Could officiate as a Deacon Teacher Priest or Elder.
Presidet Young said "I ordained most of the two or three first Quorums of the Seventies and Joseph gave me vary particular instructions to ordain them all High Priests which I did. When a man is ordained an High Priest Seventy or one of the Twelve He Can officiate in all the lesser offices of the Church whether He has been ordained to that office or not.
When I met with the Saints in Nauvoo at the first meeting after Josephs death in defending the true organization against Sidney Rigdon I had it in my mind all the time that there would have to be a Presidency of three Appointed but I knew the people Could not bear it at the time and on our return as the pioneers from the valley I Broached the subject first to Brother Woodruff and afterwords to the rest of the Quorum. They received it & finally sustained it.
[Wilford Woodruff's Journal: 1833-1898 Typescript, Volumes 1-9, Edited by Scott G. Kenney, Signature Books 1993, http://amzn.to/newmormonstudies]