Hi! I just thought I'd submit my version of this amazing song! This is how we play it at
my church. I'm a Girl (a Soprano, not a Tenor like the song is writing for), so even
though the original key is D, I usually sing it in Bb. I hope you find this helpful! :) 
Pastor Tabitha

Great I Am
Capo 3
G (320003@1)            Am7 (x02010@1)   D (xx0232@1)            Gsus4I (3x0013@1)wanna to be close, close to your side
              Am7 (x02010@1)      D (xx0232@1)       Em/GSo (322000@1)heaven is real and death is a lie
               Am7 (x02010@1)     D (xx0232@1)   G (320003@1)               Am7 (x02010@1) DI (xx0232@1)wanna hear voices of angels above,  Singing as one

Em (022000@1)          CHallelujah, (x32010@1)Holy, Holy
          G (320003@1)        Dsus4God (xx0233@1)almighty, Great I am
D (xx0232@1)    Em7               CWho (x32010@1)is worthy, None beside Thee
      G (320003@1)             Dsus4 (xx0233@1) DGod (xx0232@1)Almighty, Great I Am

//// D  Em7  C ////

G (320003@1)        Am7 (x02010@1)  D (xx0232@1)              Gsus4I (3x0013@1)wanna be near, near to your heart
            Am7 (x02010@1)   D (xx0232@1)        Em/GLoving (322000@1)the world hating the dark
            Am7 (x02010@1)       D (xx0232@1)      G (320003@1)           Am7 (x02010@1) DI (xx0232@1)wanna see dry bones living again, Singing as one

Em (022000@1)          CHallelujah, (x32010@1)Holy, Holy
       G (320003@1)             Dsus4God (xx0233@1)almighty, Great I am
D (xx0232@1)    Em7               CWho (x32010@1)is worthy, None beside Thee
          G (320003@1)           Dsus4 (xx0233@1) DGod (xx0232@1)Almighty, Great I Am

//// D  Em7  C ////
He's the Great I Am Great I Am  (2x)

Em (022000@1)The mountains shake before Him , The demons run and flee
C (x32010@1)At the mention of the name King of Majesty
G (320003@1)There is no power in hell or any who can stand
D (xx0232@1)Before the power and the presence of
              Em7                C (x32010@1)             G (320003@1) D//The (xx0232@1)Great I am,  The Great I am,  The Great I am    //

(Repeat Chorus up the octave)

Em (022000@1)          CHallelujah, (x32010@1)Holy, Holy
       G (320003@1)             Dsus4God (xx0233@1)almighty, Great I am
D (xx0232@1)    Em7               CWho (x32010@1)is worthy, None beside Thee
          G (320003@1)           Dsus4 (xx0233@1) DGod (xx0232@1)Almighty, Great I Am

//// D  Em7  C ////
He's the Great I Am Great I Am  (2x)

(Repeat bridge and Chorus, if you'd like)