Ok, I'm going to try my best to give it as close as I could interpret.
I'll start at the part that it's in harmony (as you know the song starts in harmony).
Sing through me Lord, sing through me, yo-ur heart, your sim-ple me-lo-dy
Sopranos: Sing (C#) through (C) me (Bb) Lord (Eb), sing (Eb) through (C#) meeeeee (C), yo (C#) ur (C) heart (C#), your (Bb), sim (C) ple (C#) meeee (Eb) lo (F) dy (Eb)
Altos: Sing (C#) through (C) me (Ab) Lord (Bb), sing (Bb) through (Bb) meeeeeee (Bb) eeeee (Ab), yo (C#) ur (C) hearrrrr (C) rrr (Bb), your (Bb), sim (C) ple (C#) meeee (Bb) looo (C dy (Bb)
Tenors: me (C#) Lord (G), sing (G) through (F) meeeeee (Eb) hearrrrrt (F) your (lower octave Bb) sim (lower octave C) ple (lower octave C#) meeee (G) loooo (Ab) dy (G)
I am your song God (everyone in unison the first four times)
I (C#) am (C#) your (Ab) song (Ab).....God (Ab)
I am your song God (harmony but sopranos maintain the unison in the C# chord)
Altos: I (C#) am (C#) your (Ab) song (F#....F.....Eb.....F#......) God (Eb) I (C#) am (C#) your (Ab) song (F#.....F......Eb....F#......) God (F)
Tenors: song (Bb.....C.....C#.....) God (C#) Kind of different from originally but I think it would still be nice.
Ok, now we've modulated and it changes up a little bit.
In the D chord (I am your song)
Sopranos: I (D) am (D) your (A) song (high octave D...............) God (D) , I (D) am (D) your (A) song (high octave D...........) God (D)
Altos: I (D) am (D) your (A) song (A................) God (A), I (D) am (D) your (A) song (A............) God (A)
Tenors: Song (high octave G....F#......E.......G) God (E), Song (high octave G....F#.....E......G)) God (F#)
Ending is in unison even though they do something kind of different in one part of "orchestrate" but if I was you I'd just do the end like it is in the middle of the song singing straight "orchestrate your symphony in me." And of course that depends on the skill level of your singers and how they do getting the parts of the main course of the song.
Hope that helps! If you decide to do the ending just like it is and need help I'll do the best I can but will say this: one part will have to stay in the unison while the sopranos would do D...E....F#....G...B (orchestraaaaaaaaaaaaeeeeeee Lord). So basically I gave you a rough patch of that ending. Also, I would check and make sure I gave you the parts right. If I made a mistake, charge it to my head and not my heart.
Again, hope this helps and blessings as you or whoever teaches this song. It's not easy but I'm pretty sure y'all will do fine!
